L  I  E)  HA  R.Y 
OF  THE 
U  N  I  VERS  ITY 
or  ILLINOIS 

?%1 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/textbookofscientOOpend 


TEXT-BOOK 


OF 


SCIENTIFIC  AGRICULTUHE: 


WITH 


PRACTICAL  DEDUCTIONS. 


INTENDED  FOR  THE  USE  OF  COLLEGES,  SCHOOLS,  AND 
PEIVATE  STUDENTS. 


BY 

E.  M.  PENDLETON,  M.  D. 

PROPESSOR  OP  AGRICULTURE  AND  HORTICULTURE  IN  TKB 
UNIVERSITY  OF  GEORGIA. 


NEW  YORK: 
A.  S.  BARNES  &  COMPANY, 
1875. 


Entered,  according  to  Act  of  Congress,  in  the  year  1874,  by 

B.  M.  PENDLETON,  M.  D. 
in  the  Office  of  the  Librarian  of  Congress  at  Washington. 


PKEFAOE. 


When  the  author  entered  upon  his  duties  two  years 
ago,  as  Agricultural  Professor  in  the  University  of  Georgia, 
he  found  no  text-book,  embracing  what  he  deemed  a  legiti- 
mate Agricultural  course,  to  recommend  to  his  students. 
He  had  to  gather  from  various  old  works,  and  a  few  new 
ones,  as  well  as  from  his  own  observations  and  experience, 
such  facts  and  inferences  as  seemed  to  him  best  calculated 
to  elucidate  Agricultural  Science. 

From  these  lectures  he  has  systematized  a  Text-Book 
of  Scientific  Agriculture,  for  the  use  of  his  own  classes,  or 
any  teacher  or  private  student  who  may  choose  to  adopt  it. 

He  has  not  attempted  a  practical  treatise  on  Agricul- 
ture; giving  the  processes  of  planting,  cultivating,  and 
saving  different  crops ;  but  has  endeavored  to  teach  the 
great  truths  of  Agricultural  Science,  the  foundation  of  all 
that  is  valuable  in  the  art.  For  while  much  has  been  ac- 
complished empirically,  it  has  been  done  imperfectly,  and 
at  a  heavy  cost.  Thus  while  the  agricultural  art  has 
brought  millions  from  the  soils  of  the  South,  it  has  been 
at  the  sacrifice  of  the  principal,  rather  than  the  interest,  of 
the  landed  estates.  Science  will  ultimately  restore  these 
soils,  but  it  will  take  millions  more  to  do  it,  which  must 
be  charged  to  the  blunders  of  empiricism. 

The  science  of  Yeo-etable  ISTutrition,  the  most  intricate 

B3896 


11 


PREFACE. 


as  well  as  the  moi 


presented  in  the 


clearest  possible  light,  with  the  latest  discoYcries  and  the 
best  established  theories.  A  number  of  recent  experiments 
conducted  by  the  author  will  add  much  interest,  he  trusts, 
to  this  department,  and  throw  no  little  light  on  Southern 
agriculture  especially. 

He  has  avoided  as  far  as  possible  mere  theories;  and 
proceeded  entirely  on  the  inductive  system  ;  leaving  in 
doubt  what  has  not  been  demonstrated,  for  future  experi- 
ments to  determine,  and  placing  in  bold  relief  the  great 
truths  of  Agricultural  Science  as  established  upon  un- 
doubted authority. 

Although  prepared  especially  for  Southern  students, 
the  work  is  what  it  professes  to  be,  a  Compend  of  General 
Agricultural  Science^  and  adapted  to  every  section  of  the 
country,  making  always  such  necessary  distinctions  as  may 
result  from  different  climates,  soils,  and  products. 

The  first  part  of  the  book  is  devoted  to  the  Physics  of 
Agriculture,  being  adapted  to  students  not  so  far  advanced; 
while  the  latter  part  embraces  the  more  intricate  subject 
of  Agricultural  Chemistry,  for  the  higher  classes,  who  are 
versed  in  scientific  nomenclature. 

The  author  has  aimed  at  systematic  arrangement, 
terseness  of  style,  and  simplicity  of  expression  ;  avoiding 
technicalities,  except  when  absolutely  essential  to  the 
knowledge  of  the  student.  How  far  he  has  succeeded 
must  be  left  for  an  impartial  public  to  decide. 


University  of  Georgia, 
November  9, 1874. 


OOI^TEIfTS. 


PAET  I. 

AISTATOMY  AND  PHYSIOLOaY  OF  PLANTS. 
CHAPTER  1. 

PAGE 


1.  Agriculture  Defined.     2.  Basis  of  Agricultural  Science. 

3.  Relation  of  Botany  to  Agriculture   13 

CHAPTER  II. 

4.  Vegetable  Cells.    5.  One-celled  Plants.    6.  Vegetable  Tis- 
sues   17 

CHAPTER  III. 

7.  Organs  of  Plants.    8.  Roots.   9.  Spongioles.    10.  Root  Hairs, 

etc.    11.  Offices  of  the  Roots   20 


CHAPTER  IV. 

12.  Of  the  Stem.    13.  Structure  of  the  Stem.    14.  Endogenous 

Stems.    15.  Exogenous  Stems.    16.  Offices  of  the  Stem .  25 

CHAPTER  V. 

17.  Of  the  Leaves.    18.  Offices  of  Foliage.    19.  Of  the  Stomata. 


20.  Of  Buds  ,   30 

CHAPTER  VI. 

21.  The  Flower.    22.  Fructification.    23.  Of  the  Fruit.    24.  Of 

the  Seed  T.  33 


iv 


CONTENTS. 


CHAPTER  VII. 

PAGE 

25.  Germination  of  Seed.    2G.  Plant  Growth.    27.  Nutrition  of 


the  Plantlet.   38 

CHAPTER  VIII. 

28.  Formation  and  Growth  of  Wood.    29.  Character  and  Dura- 
tion of  Plants   44 

CHAPTER  IX. 

80.  Absorption  of  Water.    31.  Exhalation  of  Water.    32.  Cir- 

culation  of  Sap.    33.  Theory  of  Electrical  Force   46 


PAET  II. 

AGRICULTURAL  METEOROLOGY. 
CHAPTER  T. 

84.  Description  of  the  Atmosphere.  35.  Its  Relation  to  the 
Vegetation.  36.  Its  Height.  37.  Pressure  of  the  Atmo- 
sphere.   38.  The  Barometer.    39.  Moisture  of  the  Atmo- 


sphere.   40.  Evaporation.    41.  Hygrometer   59 

CHAPTER  II. 

42.  Temperature.    43.  The  Thermometer.    44.  Fogs.    45.  Dew. 

46.  Frost.    47.  Snow.    48.  Hail   66 

CHAPTER  III. 


40.  Formation  of  Clouds.  50.  Height  of  Clouds.  51.  Original 
Clouds.  52.  Combined  Clouds.  53.  Causes  of  Rain. 
54.  Amount  of  Rain-fall  at  Different  Stations.    55.  The 


Rain  Gauge.    56.  Sources  of  Rain   76 

CHAPTER  IV. 

57.  Electricity.    58.  Sunlight.    59.  Air  in  Motion.    60.  Lunar 

Influence   86 


CONTENTS. 


V 


PAET  III. 


SOILS  AS  RELATED  TO  PHYSIOS. 


CHAPTER  L 

PAGE 

61.  The  Earth.     62.  The  Eocks.     63.  Geology  of  Georgia. 

64.  Disintegration.    65.  Mechanical  Action,  or  Waste. . .  94 


CHAPTER  II. 

66.  Geological  Division  of  Soils.  67.  Agricultural  Division  of 
Soils.  68.  Silicious  Soils.  69.  Clay  Soils.  70.  Calcare- 
ous Soils.    71.  Vegetable  Moulds   100 


CHAPTER  in. 

72.  Physical    Qualities,    as   Distinguished    from  Chemical. 
73.  Weight  of  Soils.    74.  Absorptive  Power  of  Soils  for 
Gases.     75.  Power  to  Remove   Salts  from  Solutions. 
76.  Adhesiveness  of  Soils.     77.  Divisibility  of  Soils. 
^     78.  Shrinking  of  Soils   105 


CHAPTER  IV. 

79.  Temperature  of  Soils.  80.  Capacity  of  Soils  for  Heat. 
81.  Retentive  Power  of  Soils  for  Heat.  82.  Permeability 
to  Water  in  Soils.  83.  Hygroscopic  Power  for  Water. 
84.  Retentive  Power  for  Water   Ill 


CHAPTER  V. 

85.  Water,  its  Mode  of  Existence  in  Soils.  86.  Of  Hydrostatic 
Water.  87.  Capillary  Water.  88.  Hygroscopic  Water. 
89.  Supply  of  Water  to  Plants.  90.  How  Plants  Absorb 
Water.  91.  Requisite  Amount  of  Water  in  Soils  for 
Plants   120 

CHAPTER  VL 


92.  Of  Drainage.     93.  Underdraining.     94.  Drainage  at  the 

South.    95.  Of  Trenching   128 


vi 


CONTENTS. 


CHAPTER  Vll. 

PAGE 

96.  Of  Ploughs.    97.  Benefits  of  Ploughing.    98.  Subsoiling. 

99.  Horizontal  culture   133 


PAET  IV. 

CHEMISTRY  OF  THE  ATMOSPHERE. 
CHAPTER  I. 

100.  Composition  of  the  Atmosphere.    101.  Oxygen,  O.  102. 


Ozone — Condensed  Oxygen.  103.  Sources  of  Ozone. 
104.  Amount  of  Ozone  in  the  Atmosphere.  105.  Rela- 
tion of  Ozone  to  Vegetation   141 

CHAPTER  II. 

106.  Hydrogen,  H.  107.  Carbon,  C.  108.  Carbonic  Acid,  CO2. 
109.  Qualities  and  Tests  of  Carbonic  Acid.  110.  Esti- 
mates of  Carbonic  Acid  in  the  Atmosphere  146 


CHAPTER  III. 

111.  Nitrogen,  N.  112.  Nitric  Acid,  NO3H.  113.  Nitric  Per- 
oxide, NO2.  114.  Generation  of  Nitric  Acid  in  the  Atmo- 
sphere. 115.  Nitrates  and  Nitrites.  116.  Nitric  Acid  in 
Rain  Water   150 

CHAPTER  IV. 

117.  Ammonia,  NH3.  118.  Ammonia  in  the  Atmosphere. 
119.  Ammonia  in  Rain  Water.  120.  Relation  of  Atmo- 
spheric Ammonia  to  Vegetation.  121.  Steam,  or  Vapor  of 
Water.  122.  Other  Atmospheric  Ingredients.  123.  Or- 
ganic Matters  of  the  Atmosphere   154 


CONTEOTS. 


vii 


PAET  V. 

CHEMISTRY  OF  PLANTS. 
CHAPTER  I. 

FAOB 

124.  Organic  and  Inorganic  Constituents.  135.  Relative  Amount 
of  each  in  Plants.  126.  Organism  of  Plants.  127.  The 
Four  Organic  Elements  in  Plants.    128.  Oxygen  in  Plants. 

129.  Effect  of  Light  on  the  Transmission  of  Oxygen. 

130.  Hydrogen  in  Plants.     131.   Nitrogen  in  Plants. 
132.  Plants  do  not  Absorb  or  Emit  Nitrogen   160 

CHAPTER  II. 

133.  Carbon  in  Plants.  134.  Decomposition  of  Carbonic  Acid 
by  Solar  Light.     135.  Fixation  of  Carbon  in  Plants. 

136.  Exhalation  of  Carbonic  Acid  in  Diffused  Light, 

137.  Supply  of  Carbonic  Acid.  138.  Carbonic  Acid  from 
the  Soil,  139.  Carbonic  Acid  as  a  Solvent.  140.  Changes 
in  Vegetable  Tissues.    141.  Tabular  View  of  the  Rela- 


tion of  Atmospheric  Ingredients  to  Plant  Life   168 

CHAPTER  III. 

142.  Inorganic  Elements  and  their  Importance.  143.  Alumina, 
AI2  O3.  144.  Manganese,  Mn.  145,  Iodine,  I.  146.  Iron, 
Fe.    147.  Silica,  Si,O==60  177 

CHAPTER  IV. 

148.  Phosphorus,  P=31.  149.  Sulphur,  S=32.  150.  Potas- 
sium, K=39.1.  151.  Sodium,  Na=23.  152.  Calcium, 
Ca=40.  153,  Magnesium,  Mg=24.  154.  Chlorine,  Cl= 
35.5   184 


CHAPTER  V. 

155.  Proximate  Principles  of  Plants.  156.  Albuminoids.  157. 
Albumen.  158.  Casein.  159.  Fibrin.  160.  Other  Ni- 
trogenous Compounds.  161.  Composition  of  Albumi- 
noids.   162.  Albuminoids  in  Crops   190 


viii 


CONTENTS. 


CHAPTER  VI. 

PAGE 

163.  Carbo-liydrates.    164.  Cellulose.   165.  Ligniii.  166.  Starch. 

167.  Inulin.    168.  Dextrin.    169.  The  Gums   196 

CHAPTER  VII. 

170.  Cane  Sugar — Saccharose.  171.  Grape  Sugar — Glucose. 
172.  Fruit  Sugar— Fructose.  173.  Milk  Sugar— Lactose. 
174.  Other  Saccharine  Substances.  175.  Alcohol  a  Pro- 
duct of  Sugar.  176.  Pectin.  177.  Changes  in  Proximate 
Principles   201 

CHAPTER  VIII. 

178.  Vegetable  Acids.  179.  Malic  Acid.  180.  Tartaric  Acid. 
181.  Citric  Acid.  182.  Oxalic  Acid.  183.  Tannic  Acid. 
184.  Acetic  Acid.  185.  Vinegar.  186.  Prussic  Acid. 
187.  Vegetable  Oils.  188.  Volatile  Oils.  189.  Fixed  Oils. 
190.  Saponification.  191.  Phosphorized  Fats.  192.  Fat 
in  Vegetable  Products   209 

CHAPTER  IX. 

193.  The  Alkaloids.  194.  Nicotine.  195.  Caffeine.  196.  Theo- 
bromine. 197.  Coloring  Matters  of  Plants.  198.  Chloro- 
phyl.....   217 

CHAPTER  X. 

199.  Density  and  Course  of  the  Sap.  200.  Ascending  and  De- 
scending Sap.    201.  Chemical  Composition  of  the  Sap. . .  221 


PAKT  YI. 

CHEMISTRY  OF  SOILS. 
CHAPTER  I. 

202.  American  and  European  Soils  Contrasted.  203.  Consti- 
tuents of  Plants  Exhausted  from  Soils.  204.  Of  Seed 
and  Plant  Constituents   224 


CONTENTS. 


CHAPTER  11. 

PAGE 


205.  Plant  Constituents  in  Minerals.  206.  Mineral  Constituents 
per  Acre,  and  their  Period  of  Exhaustion.  207.  Other 
Requisites  of  Fertility  228 

CHAPTER  III. 

208.  Coarse  and  Fine  Soils— Soluble  and  Insoluble.    209.  Of 

Soluble  Matters  in  Soils.    210.  Exhaustion  of  Soils  231 

CHAPTER  IV. 

211.  Water  Chemically  Considered.     212.   Water,  Gaseous, 

Liquid,  Solid.    213.  Chemical  Absorption  of  Soils  235 

CHAPTER  V. 

214.  Sources  of  Nitrogen.  215.  Organic  Nitrogen  in  Soils. 
216.  Compounds  of  Nitrogen  in  Soils.  217.  Ammonia  in 
Soils.  218.  Nitric  Acid  in  Soils.  219.  Nitrous  Acid  in 
Soils   239 

CHAPTER  VI. 

220.  Analysis  of  Soils  a  Dubious  Test  of  Fertility.  221.  New 
Method  of  Soil  Analysis.  222.  Deductions  from  M.  Gran- 
deau's  Experiments  246 


CHAPTER  VII. 

223.  M.  Grandeau's  Theory  Tested.     224.  Organic  Matter  a 

Means  of  Solubility.    225.  Solubility  a  Test  of  Fertility.  250 

CHAPTER  VIII. 
226.  Humus  in  Soils.    227.  Influence  of  Climate  on  Organic 


Matter  in  Soils.    228.  Humic  Acid  255 

CHAPTER  IX. 

229.  Decay.  230.  Putrefaction.  231.  Eremacausis.  232.  Fer- 
mentation. 233.  Organic  Matter  Essential  to  Fertility. 
234.  Benefits  of  Humus   259 


X 


CONTENTS. 


PAET  YII. 

FERTILIZERS  AND  NATURAL  MANURES. 


CHAPTER  L 

] 

235.  The  Subject  Introduced.  236.  Fertilizers,  how  Divided. 
237.  Special  Fertilizers.  238.  Effect  of  Fertilizers  in 
Hastening  Maturity.  239.  Nitrogen  as  a  Fertilizer.  240. 
Forms  in  which  Nitrogen  enters  Plants.  241.  Ammonia 
and  Nitric  Acid  in  Plants.  242.  Amount  of  Nitrogen  re- 
quired by  Crops  265 

CHAPTER  IL 

243.  Nitrification.  244.  Conditions  Essential  to  Nitrification. 
245.  Ammonia  a  Principal  Source  of  Nitric  Acid.  246.  Im- 
portance of  Nitric  Acid  as  a  Fertilizer  271 


CHAPTER  III. 

247.  Formation  of  Ammonia  in  Soils.  248.  Escape  of  Ammo- 
nia from  Soils.  249.  Loss  of  Ammonia  Applied  to  Crops. 
250.  Ammonia  not  Efficient  by  Itself.  251.  Ammonia 
Superior  to  the  Nitrates.    252.  Ammonia  as  a  Solvent...  276 


CHAPTER  IV. 

253.  Phosphoric  Acid,  P2O5.  254.  Sources  of  Phosphoric  Acid. 
255.  Relation  of  Phosphoric  Acid  to  Plants.  256.  Origin 
of  Mineral  Phosphates.  257.  Composition  of  Mineral  and 
other  Phosphates   283 


CHAPTER  V. 

258.  Manufacture  of  Superphosphates.  259.  Hydrus  Sulphuric 
Acid,  SO3HO.  260.  Composition  of  Superphosphates. 
261.  Bi-Phosphate  of  Lime,  CaO^HO,  PO5.  262.  Home- 
made Superphosphates.  263.  Effect  of  Liquid  Bi-Phos- 
phate of  Lime  as  a  Fertilizer.   264.  Precipitated  Phos- 


CONTENTS.  xi 

PAGE 

phate  of  Lime.  265.  Reduced  Phosphates.  260.  Experi- 
ments with  Reduced  and  Unreduced  Phosphate.  267.  Am- 
moniated  Superphosphate  289 

CHAPTER  VI. 

268.  Potassa,  Ko.  269.  Chloride  of  Potassium.  270.  Soda, 
Na20.  271.  Lime,  CaO.  272.  Sulphate  of  Lime,  CaO, 
SO32HO.  273.  Magnesia,  MgO.  274.  Sulphuric  Acid  as 
a  Fertilizer.  275.  Chlorine,  CI.  276.  Chloride  of  Sodium 
as  a  Fertilizer  j  303 

CHAPTER  VII. 
277.  Natural  Manures.     278.  Stable  Manure.     279.  Composi- 


tion of  Stable  Manure.  280.  Saving  and  Composting 
Manures.  281.  Chemical  Changes  in  Manure  Heaps. 
282.  Night  Soil.  283.  Hurdling  System.  284.  Cotton 
Seed  as  a  Manure.  285.  Experiments  with  Cotton  Seed. 
286.  Wood  Ashes  ,   312 

CHAPTER  VIII. 

287.  Green  Manures.  288.  Value  of  Mineral  Substance  in  Or- 
ganic Matter.  289.  Absorption  and  Oxidation  of  Nitrogen 
by  Carbonaceous  Matters.  290.  Rotation  of  Crops.  291. 
Plants  Differently  Constituted.  292.  Benefit  of  Resting 
Lands.  293.  Best  Rotation  in  Cotton  Culture.  294.  De- 
ductions from  Experiments   326 


PAET  YIII. 

ANIMAL  NUTRITION. 
CHAPTER  I. 

295.  Experiments  in  Germany.  296.  Proximate  Composition  of 
Animal  Substances.  297.  Flesh  Formers  and  Fat  Form- 
ers. 298.  Proportion  of  Different  Foods  Digested  by 
Animals.  299.  Mixing  Carbo-hydrates  and  Albuminoids 
as  Food.   300.  Laws  which  Govern  Flesh  Building   341 


Xll 


CONTENTS. 


CHAPTER  II. 

PAGE 

801.  Respiration  Apparatus.  302.  Digestion  of  Crude  Fibre. 
303.  Experiments  on  the  Production  of  Milk.  304.  Ex- 
periments in  Butter-Making.  305.  Preservation  and  Con- 
densation of  Milk   348 

CHAPTER  III. 

806.  Fuel  and  Food  for  the  Animal  System.  307.  Importance 
of  Mixing  Cattle  Foods.  308.  Nutritiousness  of  Wheat 
Bran.  309.  Cotton-Seed  Meal.  310.  Fodder  Corn.  311. 
Relative  Value  of  Cattle  Foods  as  Provender   353 


APPENDIX. 

1.  The  Cotton  Plant.  2.  Indian  Corn.  3.  Wheat.  4.  The  Oat. 
5.  The  Grasses.  6.  The  Tobacco  Plant.  7.  The  Cryp- 
togams. 8.  Water  Culture.  9.  Tables  of  Agricultural 
Products   359 


ACKNOWLEDGMENTS. 


In  consulting  authorities,  it  is  difficult  for  an  author  always  to  distinguish 
between  what  is  original  and  what  is  borrowed.  In  science,  many  ideas  have  no 
paternity,  and  are  adopted  as  the  common  property  of  mankind.  In  this  work 
the  author  has  endeavored  to  give  credit  to  every  one  known  to  be  original. 

He  feels  particularly  indebted  to  the  two  able  works  of  Prof.  Johnson,  How 
Crops  Grow,  and  How  Crops  Feed,  for  much  valuable  information  compiled 
from  late  European  authorities  on  vegetable  Physiology  and  Nutrition,  as  well 
as  the  Chemistry  of  Plants  and  Soils.  Also  to  Prof.  Morfit's  new  and  valuable 
book,  Pure  Fertilizers. 

For  the  more  recent  contributions  to  agricultural  science,  now  being  demon- 
strated at  the  Experimental  Stations  of  Germany,  France,  and  England,  the 
author  is  under  special  obligations  to  the  Monthly  Reports  of  the  Department  of 
Agriculture  at  Washington. 

Besides  these,  the  following  works  have  been  consulted  by  him  with  profit : 
American  Farmer's  Encyclopcedia,  Liebig's  Agricultural  Chemistry,  Johnston''s 
Agricultural  Chemistry,  CaldwelVs  Agricultural  Chemical  Analysis,  Liebig''s  Laws 
of  Husbandry,  StockhardVs  Agricultural  Chemistry,  Gray'' s  Field  Book  of  Botany, 
Wood's  Botanist  and  Florist,  Graham's  Chemisti^,  Fresenius''  Chemical  Analysis, 
BoussingaulV s  Rural  Economy,  Liebig's  Modern  Agriculture,  Sibson's  Agricultural 
Chemistry,  Barbee's  Cotton  Question,  Harris's  Insects  Injurious  to  Vegetation,  Al- 
len's  American  Farm  Book,  Hilgard's  Agriculture  and  Geology  of  Mississippi,  Ken- 
tucky  Geological  Reports,  Ville's  High  Farming  without  Manure,  Shepard's  Min- 
eralogy, Brockelsby's  Meteorology,  Tenney's  Geology,  White's  Statistics  of  Georgia, 
American  Weeds  and  Useful  Plants,  Smithsonian  Reports,  Southern  Cultivator, 
{published  at  Athens,  Georgia,)  Rural  Carolinian,  {Charleston,  South  Carolina,)  and 
American  Farmer,  Baltimore, 


PHILIP  S.  CHAPPELL,  Esq., 

OF  BALTIMOKE, 

THIS  WORK  IS  RESPECTFULLY  DEDICATED,  AS  A  TOKEN  OF  ESTEEM, 
AND  A  TRIBUTE  TO  HIS  KINDLINESS,  LIBERAI.ITY,  AND 
INTEGRITY,  BY 

THE  AUTHOR. 


PAET  L 

ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


CHAPTEK  I. 

!  ■ 

I /LGEICULTUKE  DEFIXED. — BASIS  OF  AGRICULTURAL  SCIENCE. 
\'i  RELATION  OF  BOTANY  TO  AGRICULTURE. 

1.  Agriculture  Defined, 

Agriculture  is  the  art  or  science  of  cultivating  the 
-^^oil  ;  the  term  being  derived  from  the  Latin  ciger^  a  field, 
I  and  cultura^  cultivation.    Ifi  its  widest  scope  it  embraces 
[jtiot  only  the  cultivation  of  the  soil  and  the  chemistry  and 
physiology  of  farm  plants,  but  the  natural  history  of  all 
iomestic  animals ;  the  best  mode  of  utilizing  their  labor 
md  food,  as  well  as  their  flesh,  milk,  tallow,  hides,  etc. ; 
md  the  climatic,  atmospheric,  and  telluric  influences  afiect- 
mg  plant  life. 

An  agriculturist  is  one  learned  in  the  principles  of 
agricultural  science.  A  farmer,  husbandman,  or  culti- 
vator 23ursues  the  art  simply  as  an  occupation.  The  same 
distinction  exists  between  the  machinist  and  the  factory 
)perative.  The  one  understands  the  science  of  mechanics, 
^md  can  repair  and  reconstruct  the  machinery ;  the  other 
iSGS  the  tools  and  applies  the  art.  So  does  the  farmer ; 
.rvhile  the  agriculturist  is  supposed  to  understand  all  the 
orocesses  of  fertilizing  and  restoring  worn  soils,  and  utiliz- 
|ng  the  labor  and  culture  of  a  farm. 


14 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


Agriculture  then  may  be  taught  both  as  a  science  and 
art.  The  former  teaches  a  man  why  it  is  necessary  to 
plough;  the  latter,  the  process  of  ploughing.  The  art 
teaches  how  to  jDlant,  cultivate,  and  husband  crops ;  the 
science,  of  what  they  are  composed,  and  how  they  are  de- 
rived from  the  soil  and  atmosphere.  The  effect  of  the  art 
is  to  wear  out  the  soil  by  constant  cropping ;  science  will 
restore  it  to  its  pristine  fertility. 

The  agricultural  art  has  been  pursued  by  all  enlight- 
ened nations  since  the  curse  was  pronounced  "by  the 
sweat  of  thy  face  shalt  thou  eat  bread."  The  Egyptians 
and  the  Jews  were  the  earliest  nations  which  fostered  it. 
The  Greeks  and  Romans  improved  much  upon  them,  and 
advanced  it  almost  abreast  with  the  German  and  English 
methods  of  the  last  century.  Up  to  near  its  close  the 
whole  process  of  cultivation  was  empirical.  About  that 
period  several  eminent  agricultural  scientists  made  their 
appearance,  as  Bergen,  Thaer,  De  Saussure,  and  Dundon- 
ald.  Sir  Humphry  Davy  delivered  the  first  course  of  lec- 
tures on  agricultural  chemistry  at  London,  in  1812.  Baron 
Liebig  improved  upon  him,  and  during  a  long  lifetime 
accomplished  much  for  agricultural  science. 

Agriculture  is  not  a  pure. science,  like  mathematics ;  but 
a  mixed  science,  like  medicine,  made  up  from  a  number  of 
collateral  sciences.  Among  these,  the  most  prominent  are 
Botany,  Physiology,  Chemistry,  Physics,  Meteorology, 
Mineralogy,  and  Geology.  All  of  these,  and  some  others, 
such  as  Zoology,  Entomology,  Rural  Architecture,  and  Me- 
chanics, are  involved  to  some  extent  in  making  up  what 
is  termed  Agricultural  Science. 

In  fact,  so  many  of  the  physical  sciences  are  interblended 
with  agriculture,  and  collateral  to  it,  that  it  may  be  con- 
sidered in  its  most  extended  bearing  as  a  comprehensive 
system  of  Natural  Science. 


BASIS  OF  AGEICULTURAL  SCIENCE. 


15 


2.  Basis  of  Agricultural  Science. 
The  science  of  Agriculture  (indeed,  all  1^^'atural  Science) 
has  to  do  with  Matter  and  the  Forces  which  move  matter. 

The  distinct  forces  now  recognized  in  nature,  are  either 
physical,  chemical,  or  physiological. 

Ph3i^ical  forces  are  those  which  change  matter  as  to 
its  situation  without  affecting  its  qualities. 

Chemical  force  changes  the  nature  and  qualities  of 
matter  by  composition  or  decomposition. 

Physiological  or  organic  force  develops  the  life,  growth, 
I  and  sustenance  of  living  organisms. 

The  Physical  forces  may  be  divided  into  the  loichictive  : 
■Light,  Heat,  Electricity,  and  Magnetism.    The  Cosmical: 
■  Gravitation.    The  Molecular:  Crystallization,  Cohesion, 
Adhesion,  Solution,  and  Osmose. 

Although  several  of  these  are  the  result  of  chemical 
j  action,  yet  there  is  but  one  well-defined  chemical  force, 
I  viz.:  Affinity. 

There  is  also  but  one  jDhysiological  force,  Vitality. 
All  matter  then  is  either  organic  or  inorganic. 
Oiganized  bodies  differ  from  inorganic  in  possessing 
the  vital  force,  through  which  they  grow  by  the  absorption 
of  food,  and  by  which  they  reproduce  themselves. 
,     Plants,  like  animals,  are  organized  bodies,  and  have 
^ their  anatomical  and  physiological  relations. 

3.  Relation  of  Botany  to  Agriculture, 
The  science  of  Botany  comprehends  all  that  relates  to 
'she  vegetable  kingdom  ;  and  whatever  of  it  that  has  a 
ilirect  or  indirect  bearing  on  Agriculture,  maybe  jDroperly 
:ermed  Agricultural  Botany.  This  embraces  the  Struc- 
ture of  Plants,  Vegetable  Physiology,  and  so  much  of 
systematic  Botany  as  describes  all  plants  which  are  culti- 
•  ated  and  deemed  useful  to  man. 


16  ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


In  what  is  termed  the  Natural  System,  all  plants  are 
divided  into  two  Series  :  1st.  Phenogams^  flowering  plants, 
producing  seeds.  2d.  Cryptogams^  plants  without  flow- 
ers, reproducing  their  species  by  sporeSy  which  are  mostly 
single  cells.  In  this  Series  is  embraced  mushrooms,  lichens, 
ferns,  sea-weeds,  mosses,  liverworts,  moulds,  algaa,  and  fungi. 

Series  are  divided  into  Classes,  by  the  germ,  the  stem, 
the  leaves,  and  the  flowers  :  they  are  the  Exogens^  or  out- 
side growers^  and  the  Endogens^  or  inside  groioers. 

Classes  are  divided  into  Families  or  Orders,  which 
contain  groups  agreeing  in  many  points,  but  yet  essentially 
different,  as  the  okra,  the  hollyhock,  and  cotton. 

Orders  embrace  Genera,  which  have  the  same  charac- 
ters in  common  distinguishing  them  from  all  other  plants  ; 
thus  all  the  oaks  belong  to  the  same  genus.  Species  bring 
them  still  nearer  together,  in  w^hich  animals  or  plants, 
though  of  different  varieties  or  sub-species^  possess  in  com- 
mon the  power  of  reproduction. 

'Varieties  occur  in  the  same  species  from  numerous 
causes,  such  as  scarcity  or  abundance  of  nutriment  (by 
which  dwarfs  or  giants  are  made),  difference  in, climate, 
etc. ;  but  often  they  are  beyond  explanation.  Some  plants, 
as  the  cereals,  beans,  peas,  etc.,  may  be  reproduced  fron: 
their  seed ;  while  others,  as  apples,  grapes,  etc.,  are  betteii 
perpetuated  as  to  variety  from  cuttings,  layers,  or  grafts 
This  may  be  owing  to  unavoidable  contact  wdth  the  j^ol  1 
len  of  other  varieties,  but  doubtless  in  some  cases  there 
exists  inherent  disability. 

Hybrids  are  sometimes  produced  in  plants  as  well  a^ 
animals  ;  the  pollen  of  one  species  fertilizing  the  ovule  of 
another.  The  limit  of  hybridization  is  very  narrow,  fecun 
dation  taking  place  only  in  species  which  are  very  closel} 
allied.  Mere  mixing  of  different  kinds  of  corn,  melons 
etc.,  does  not  amount  to  hybridization. 

Botany  requires  two  names  for  a  plant,  one  to  indicate 
the  genuSy  the  other  the  species.    Thus  in  Quercus  albd 


VEGETABLE  CELLS.  17 

J  (the  white  oak),  the  first  name  indicates  the  genus,  the 
V  . second  the  species. 

The  names  of  some  families  are  derived  from  the  form 
or  arrangement  of  the  flower  ;  thus  the  pulse  family,  in- 
cluding clover,  the  bean,  pea,  and  vetch,  is  called  FapiliO' 
,naceous,  because  their  flowers  resemble  the  butterfly.  The 
mustard  family,  also  embracing  the  radish,  turnip,  and 
cabbage,  are  called  Cruciferoics,  because  their  flowers  have 
four  petals  resembling  the  four  arms  of  a  cross. 

Composite  plants  are  so  called  when  their  flowers  are 
arranged  on  an  expanding  stem,  side  by  side,  in  great 
numbers;  as  the  sunflower,  artichoke,  thistle,  etc. 

The  Coniferous  embrace  the  fir,  pine,  larch,  etc. ;  their 
flowers  being  arranged  in  conical  receptacles. 

Tlmldliferous  plants  have  the  flowers  radiating  from 
a  centre,  like  the  ribs  of  an  umbrella,  as  the  caraway,  car- 
rot, parsnip,  etc. 

CHAPTER  II. 

VEGETABLE  CELLS.— ONE-CELLED  PLANTS.— VEGETABLE 
TISSUES. 

4.    Vegetable  Cells, 
The  microscope  has  revealed  that  all  organized  struc- 
tures,  whether  animal  or  vegetable,  originate  in  minute 
vesicles  or  cells.    The  cell  structure  is  an  aggregation  of 
^  little  globular  vesicles,  more  or  less  filled  with  liquid  or 
solid  substances. 

^  Cell  formation  is  very  rapid  in  some  cases  ;  most  strik- 
.ing  in  the  mushroom  family.    Some  as  large  as  a  peck 

measure  are  produced  in  one  summer  night,  at  the  rate  as 

estimated  of  several  hundred  millions  of  cells  in  one  hour. 

^  Buds,  leaves,  and  flowers,  and  the  tip  of  roots  in  a  grow- 
ling state,  show  very  distinctly,  ^the  process  of  cell  forma- 
.  tion  under  the  microscope. 


18 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


The  protoplasm^  a  semi-fluid  mucilaginous  substance, 
is  the  formative  layer  of  the  cell.  From  it  is  developed 
the  nucleus  and  nucleolus. 

The  m^cleus  is  a  small  rounded  body  within,  and  sur- 
rounded by  the  protoplasm  which  lines  the  cell. 

The  nucleolus  is  a  minute  globe  within  the  nucleus. 

The  cell  wall  consists  of  a  substance  called  cellulose^ 
which  is  composed  chiefly  of  carbon.  In  some  cases  there 
are  no  cell  walls,  but  the  cells  consist  of  the  protoplasm 
and  nucleus. 

The  protoplasm  and  matters  dissolved  in  the  juices  of 
the  plant  are  transformed,  and  result  in  the  production  of 
solid  substances. 

The  processes  of  plant  development  may  be  observed 
under  the  microscope,  such  as  the  formation  and  growth 
of  starch  grains  and  the  matters  which  give  color  to  leaves 
and  flowers.  At  first  there  are  no  solid  matters  except 
the  nucleus  and  protoplasm.  Then  appear  green  grains 
of  chlorophyl,  completely  hiding  the  nucleus.  Then  these 
grains  lose  their  green  color  and  assume  the  character  of 
starch.  As  the  seed  hardens,  the  microscope  reveals  the 
change  of  the  starch  grains  into  cellulose.  The  nucleus 
disappears,  and  more  starch  grains  appear  ;  which  in  their 
turn  become  converted  into  smaller  grains  of  aleurone, 
which  completely  occupy  the  cells  at  the  maturity  of  the 
seed. 

Similar  transpositions  take  place  reversely  in  the 
sprouting  of  the  seed.  The  nucleus  again  appears,  the 
aleurone  is  dissolved,  and  even  the  cellulose  is  converted 
into  soluble  food  for  the  seedling.  These  facts  were  ob- 
served from  experiments  with  the  common  nasturtium 
(Tropoeolum  majus)  by  Hartig. 

Vegetable  cells  are  quite  variable  in  dimensions.  A 
marine  plant  (Caulerpa  prolifera)  has  a  single  cell  some- 
times a  foot  in  length.  In  most  cases,  however,- they  are 
less  than        of  an  inch  in  diameter ;  many  of  them  much 


OXE-CELLED  PLAXTS. 


19 


smaller.  The  pulp  of  an  orange  is  a  fine  example  of  cell 
tissue  on  a  large  scale,  it8  cells  being  about  one-fourth  of 
an  inch  in  length. 

Every  fibre  of  cotton  is  a  distinct  cell.  Wood  cells  are 
mostly  elongated,  tapering  at  both  ends.  In  the  bark  of 
many  trees,  and  stems  and  leaves  of  grasses,  they  are  rec- 
tangular. 

Although  cells  show  no  apertures  under  the  strongest 
microscope,  they  are  known  to  be  permeable  to  liquids.  A 
thin  slice  of  potato  immersed  in  water,  if  touched  with  a 
drop  of  iodine  solution,  will  exhibit  a  rapid  transfusion  of 
the  iodine  through  all  the  unbroken  cells. 

5.  One-celled  Flcints, 

Some  plants  of  the  lower  orders  are  known  to  exist 
with  a  single  cell,  while  others  are  constituted  of  cells 
through  every  stage  of  their  existence.  What  is  known 
as  red  siioic  of  the  Arctic  regions,  is  common  snow  colored 
with  a  one-celled  microscopic  plant. 

The  flocculent  mould  which  gathers  in  the  solutions  of 
certain  salts,  as  those  of  sulphate  of  soda  and  magnesia, 
are  seen  to  be  under  the  microscope,  vegetation  of  one 
cell,  rapidly  formed.  And  this  is  true  of  brewer's  yeast, 
some  of  which  has  only  a  few,  and  some  but  one. 

Mushrooms,  sea-w^eeds,  the  mould  of  damp  walls,  old 
cheese,  etc.,  constitute  similar  developments  of  vegetable 
life.  While  some  of  the  fungi  and  parasites  wdiich  prey 
upon  plants  are  also  produced  in  the  same  way. 

In  one-celled  plants  the  new  cell  buds  out  from  the 
parent  cell  and  becomes  detached  from  it.  In  higher 
plants  no  separation  takes  place,  save  the  adhering  tissue 
formed  between  the  cells. 

6.  Vegetable  Tissues, 

In  the  higher  order  of  plants,  where  the  cells  cannot 
be  well  separated,  they  form  a  coherent  mass,  attached 


20 


AXATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


more  or  less  firmly,  known  as  vegetahle  tissue,  A  large 
number  have  been  named  by  vegetable  anatomists,  based 
upon  their  different  forms  or  functions  ;  the  principal  of 
which  are  Cellular  Tissue,  Vascular  Tissue,  Woody  Tissue, 
and  Bast  Tissue. 

Cellular  Tissue  is  the  base  of  all  vegetable  structure, 
and  is  constituted  of  globular  or  polyhedral  cells.  This 
is  the  only  form  of  tissue  in  the  simpler  kinds  of  plants. 
Cell  tissue  and  parenchyma  are  synonymous  terms. 

Wood  tissue  consists  of  long,  spindle-shaped  cells,  taper- 
ing at  each  end.  They  overlap  each  other^  constituting 
the  tough  fibres  of  wood.  They  are  often  thickened  by  cel- 
lulose, lignin,  and  coloring  matters. 

Vcfscular  Tissue  is  formed  from  a  simple  transposition 
of  cellular  tissue,  and  embraces  the  tubes  and  ducts  of  the 
higher  kinds  of  plants.  These  ducts  are  dotted^  ringed, 
angular,  and  spiral. 

Bast  Tissue  is  so  named  because  it  is  found  only  in  the 
hast  or  inner  bark.  It  resembles  w^ood  tissue,  but  is  more 
flexible  and  delicate.  Linen,  hemp,  and  all  flexible  mate- 
rial except  cotton,  is  constituted  of  this  tissue.  Bast  cells 
are  to  the  rind  what  wood  cells  are  to  the  wood.  All 
elongated  cells  like  the  two  last  are  called  prosenchyma. 


CHAPTEE  III. 

ORGANS  or  PLANTS.  ROOTS.  SPONGIOLES. — ROOT  HAIRS. 

OFFICES  OF  THE  ROOTS. 

'Z.    Organs  of  Plants, 
The  Compound  Organs  of  Plants  are  divided  into 
Vegetative  and  Reproductive.    To  the  vegetative  belong 
the  Roots,  the  Stems,  and  the  Leaves.    To  the  reproduc- 
tive, the  Flower,  and  the  Fruit,  which  embraces  the  Seed. 


ROOTS. 


21 


8.  Boots. 

The  Root  is  properly  the  desceiiding  axis  of  the  plant, 
as  the  Stern  is  its  ascending  axis. 

The  roots  grow  downward  into  the  soil  and  seek  a  moist 
medium.  They  can  develop  fully  in  light,  though  it  is 
unfavorable  to  them.  They  increase  mostly  by  elongation. 
About  \  of  an  inch  from  the  tip  is  in  the  formative  grow- 
ing state.  When  this  is  cut  off,  the  root  does  not  extend, 
but  branches  off. 

Dicotyledonous  plants^  or  Exogens^  have  tap  roots 
descending  vertically  into  the  ground.  Sometimes  these 
roots  are  very  long,  having  two  lateral  branches  ;  others 
short,  being  smaller  than  their  side  roots.  The  pine  and 
fir  tree,  cotton  j^lant,  radish,  carrot,  etc.,  are  examples  of 
the  tap  root.  Trees  of  this  species  draw  their  nourish- 
ment from  many  feet  below  the  surface. 

Tap  roots  throw  out  lateral  roots  from  their  base  to 
their  extremities,  which  again  subdivide  into  branches. 
The  lateral  roots  near  the  surface,  Avhicli  permeate  the 
tilth  (as  of  the  cotton  plant)  are  much  larger,  and  liave 
many  more  rootlets  than  lower  down. 

Monocotyledonoiis  plants^  or  Endogens^  have  what  are 
termed  crown  roots,  which  branch  directly  from  the  base 
of  the  stem.  The  cereals,  grasses,  and  Indian  corn,  are 
examples. 

Tlie  Fibrils^  also  called  Feeders,  are  small  thread-like 
rootlets  which  branch  out  in  many  directions  from  the 
older  I'oots.    They  are  the  last  formed,  are  only  a  few 

*  inches  in  length,  and  permeate  in  some  cases  (as  in  cotton 

S  and  corn)  the  whole  surface  of  the  ground  in  quest  of  food. 

E  They  generally  extend  as  far  from  the  plant  as  the  height 

1  of  the  stem. 

'  9.  Spongioles. 

^       The  tips  of  the  rootlets  are  called  spongioles^  or  sponge- 
lets.    They  do  not  suck  up  the  food  from  the  soil,  as  their 


22 


AXATOMY   AXD  PHYSIOLOGY  OF  PLANTS. 


name  indicates,  but  merely  protect  the  true  end  of  the 
root,  being  formed  of  detached  cells  like  an  elastic  cushion. 
They  soon  perish  when  this  office  is  fulfilled.  They  are 
filled  with  air  instead  of  sap.  This  air  cap  is  much 
larger  in  diameter  than  the  true  root  is,  w^hich  shrinks  as 
it  matures. 

10.  Hoot  Hairs^  etc. 

Some  plants,  the  mustard  for  instance,  have  root  hairs 
on  their  roots,  scarcely  visible,  which  absorb  their  food. 
These  hairs  are  more  numerous  in  poor  than  in  rich  soils. 
Other  plants,  as  the  onion,  which  have  no  root  hairs,  absorb 
food  by  the  delicate  texture  and  greater  number  of  rootlets. 

The  contact  of  root  hairs  and  rootlets  wdth  the  soil  is 
very  intimate,  and  often  inseparable. 

Roots  may  further  be  divided  according  to  the  medium 
in  which  they  grow;  as  soil  roots,  w^ater  roots,  and  air  roots. 

Soil  roots,  which  are  common  to  all  agricultural  plants, 
perish  in  air  and  rot  in  water.  The  roots  of  aquatic  plants 
flourish  in  water,  and  die  when  removed  from  it,  or  from 
earth  saturated  with  it. 

Air  roots  are  common  only  to  tropical  plants.  Indian 
corn  is  an  exception,  which  throws  out  brace  roots  through 
the  air  from  the  lower  joints  into  the  soil.  The  banyan 
of  India  sends  down  roots  from  its  branches  to  the  earth  ; 
and  other  tropical  plants,  as  the  Orchids,  send  out  roots 
into  the  air  which  never  penetrate  the  water  or  the  soil. 
The  Zamia  spiralis  throws  out  lateral  air  roots  from  the 
crown  of  its  tap  root,  which  sends  branches  down  into  the 
earth  and  others  up  into  the  air. 

Some  plants,  as  rice,  may  be  termed  amphibious,  hav- 
ing roots  which  luxuriate  either  in  water  or  soil.    So  of  j 
willow  and  alder  trees  ;  parts  of  their  roots  do  well  in 
water,  and  part  equally  well  in  soil  comparatively  dry.  ! 

Roots  vary  as  to  the  relative  amount  of  the  whole  | 
plant,  according  to  the  age  and  character  of  the  plant.  | 

Schubart  found  the  roots  of  wheat,  as  comjDared  to  the  I 


OFFICES  OF  THE  ROOTS.  23 
# 

entire  plant,  to  be  40  per  cent,  the  last  of  April.  Peas  44 
per  cent,  four  weeks  after  sowing — Avhen  in  bloom,  24  per 
cent. 

The  length  of  roots  also  varies  according  to  the  char- 
acter and  fertility  of  soil.  Hellriegel  estimated  the  length 
of  the  roots  of  a  vigorous  barley  stalk  in  a  porous  garden 
soil  at  128  feet,  an  oat  plant  158  feet.  In  a  coarse  com- 
pact gravel  soil,  the  barley  plant  had  but  80  feet  of  roots. 

The  internal  structure  of  the  roots  corresponds  with 
that  of  the  stem,  and  will  be  described  under  that  head. 

11.    Offices  of  the  Boots, 

Roots  have  three  offices  :  1st,  to  fix  the  plant  or  tree  in 
the  earth  and  maintain  its  upright  position  ;  2d,  to  absorb 
nutriment  from  tlie  soil ;  3d,  to  hold  it  for  future  use. 

The  brace  roots  of  maize  seem  to  have  but  little  else  to 
do  than  to  hold  up  the  plant;  while  the  tap  roots  of  the  tur- 
nip, carrot,  and  beet  act  as  store-houses  for  sugar,  pectose, 
etc.,  with  Avhich  to  supply  the  stem,  flower,  and  seeds  the 
second  year;  hence  their  value  in  fattening  stock. 

The  older  and  larger  roots  act  as  vehicles  for  the  fibrils 
to  convey  the  food  taken  up  by  them  to  the  stems  and 
leaves. 

Roots  are  variously  constructed,  so  as  to  absorb  food 
from  the  soil.  All  of  the  young  and  delicate  parts  of  the 
roots  are  engaged  in  this  work  except  the  extreme  ends. 
Old  roots,  es23ecially  of  perennial  plants,  become  hard  and 
lose  this  quality.  The  amount  of  absorbing  surface  de- 
pends largely  upon  the  rapidity  of  extension  and  length 
of  the  rootlets.  This  is  due  to  several  contingencies,  as 
the* moisture  and  fertility  of  the  soil.  In  a  poor  soil,  the 
absorbing  surface  would  be  much  less  than  in  a  fertile  soil. 
And  so  of  a  dry,  compared  to  a  moist  soil. 

Nobbe  proved  by  experiments  in  glass  cylinders  with  a 
poor  clay  soil  manured  near  the  surface,  that  the  roots 
would  form  there  in  thick  masses,  while  very  few  extended 


24  ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 

! 

into  the  poor  soil  beneath.  The  manure  being  placed  in 
the  bottom  of  the  cylinder,  the  whole  thing  was  reversed. 
Long  slender  roots  put  out  through  the  i^oor  soil,  till  they 
reached  the  manure,  and  then  formed  a  perfect  network  of 
fibrils  in  quest  of  food,  which  greatly  invigorated  the  plant. 

The  first  root  branches  are  sent  out  bv  the  visror  of  the 
plant  itself,  without  reference  to  the  soil  they  penetrate,  j 
Afterward,  they  increase  and  extend  according  to  the  fer- 
tility of  the  soil.   When  there  is  no  nourishment  they  soon 
perish. 

The  office  of  the  air  roots  is  in  doubt.  Duchartre  denies 
tlieir  power  to  absorb  moisture,  w^hich  is  sustained  in  the 
fact  that  they  only  grow  in  humid  air  where  the  plants 
have  plenty  of  water. 

De  Candolle  contended  that  plants  have  excretory  roots 
to  throw  off  substances  injurious  to  them.  Dr.  Gyde  trans- 
planted to  water  healthy  plants,  w^hich  imparted  sub- 
stances to  it  similar  to  their  sap,  and  hence  inferred  excre-  j 
tive  powers.  This  may  have  resulted  from  disorganized  I 
root  hairs,  produced  by  the  change  of  the  medium.  It  is 
not  probable  that  healthy  plants  excrete  at  all. 

Henrici  made  experiments  with  a  young  raspberry,  to 
prove  that  plants  sent  out  roots  after  water.  It  was  put 
in  a  glass  funnel  filled  with  soil,  on  a  jar  containing  water. 
In  several  w^eeks,  four  strong  roots  penetrated  the  paper 
stopper  of  the  funnel,  and  pushed  down  into  the  water, 
Avhere  they  threw  oat  many  lateral  roots,  apparently  to 
supply  water  to  the  plant. 

Some  plants,  as  the  bean,  squash,  and  maize,  after  being 
itairly  sprouted,  will  develop  without  soil  if  the  roots  are 
kept  in  water  and  supplied  with  soluble  food.  Such  plants 
will  soon  perish  transplanted  to  a  common  arable  soil. 
And  the  roots  of  soil  plants  placed  in  water  will  also  die, 
new  roots  putting  forth  adapted  to  water.  A  sudden 
change  will  produce  the  death  of  the  plant.  (Dr.  Sachs.) 
Nobbe  could  discover  no  structural  difference  between  the 


OF  THE  STEM. 


25 


roots  of  buckwheat  which  grew  in  water  and  those  which 
grew  in  soil. 

Sachs  found  that  roots  die  from  a  change  of  medium 
from  mechanical  injury  to  the  fibrils.  When  the  roots  are 
preserved  intact  the  plants  do  not  die. 


CHAPTEE  IV. 

OF  THE  STEM. — ITS  STEUCTURE.  ENDOGENOUS  STEMS. 

EXOGENOUS   STEMS.  OFFICES  OF  THE  STEM. 

12.    Of  the  Stem, 

The  Stem  makes  its  appearance  soon  after  the  seed 
germinates  and  the  rootlets  appear.  It  has  an  upward 
direction  at  first,  which  some  retain,  while  others  are 
horizontal.  Some  are  recumbent,  as  if  too  weak  to  stand, 
like  the  sanfoin  ;  others  procumbent,  or  trailmg,  as  the 
Bermuda  grass ;  others  creeping  or  climbing,  as  the  pea, 
cucumber,  ivy,  grape;  others  twine,  coiling  themselves 
around  pillars,  trees,  etc.,  as  the  morning  glory,  poison 
oak  (Rhus  toxicodendron),  hop  vine,  etc. 

Runners^  as  in  the  strawberry,  and  layers^  as  in  the 
currant,  are  horizontal  stems,  which  branch  out  and  take 
root  and  serve  for  propagation.  The  tillering  of  wheat 
and  other  small  grain  is  similar  to  layering  ;  the  branch- 
ing stems  in  some  cases  producing  50  or  60  grain-bearing 
culms  from  one  seed. 

The  cereals  and  grasses  have  unbranched  stems  called 
culms.  Their  leaves  clasp  the  stems  at  the  base  of  each 
joint,  which  is  a  thickened  knot  called  the  node.  The 
internode  is  the  stem  between  the  nodes.  Other  agricul- 
tural plants  have  branching  stems,  as  well  as  all  trees  of 
temperate  zones.  They  have  also  side  stems,  which  are 
again  subdivided  into  branchlets. 
2 


26  ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


kStems  also  exist  under  ground.  The  peanut  is  a  striking 
instance.  As  soon  as  the  bloom  falls,  the  liower-stems 
lengthen,  penetrate  the  earth,  ripening  their  fruit  in  the 
soil. 

Hoot  stocks  are  stems  which  creep  under  the  soil,  put- 
ting out  fresh  roots  at  each  node.  The  bloodroot  (San- 
guinaria  Canadensis)  and  quack  grass  are  examples.  The 
raspberry,  rose,  and  cherry  have  suckers  springing  out 
from  the  centre  root  similar  to  the  root  stock. 

Tubers  of  the  Irish  potato  and  artichoke  are  enlarge-  j 
ments  of  underground  stems.    They  serve  vv^ell  for  propa-  j 
gation,  each  eye  forming  the  germ  of  a  new  plant.    J^ulbs  j 
are  also  examples  of  thickened  stems,  as  the  onion,  the 
dahlia,  etc. 

13.  Structure  of  the  Stem, 

The  structure  of  the  stem  is  complicated.  The  rudi-  • 
mentary  stem  found  in  the  seed  consists  of  cellular  tissue, 
an  aggregation  of  cells,  which  multiply  rapidly  during 
the  active  growth  of  the  plant.  In  the  lower  plants,  as 
mushrooms,  lichens,  etc.,  the  stems  are  purely  cellular.  In 
flowering  plants  this  gives  way  to  vascular  tissue,  con- 
sisting of  ducts  and  tubes  which  are  in  close  connection, 
arranged  in  bundles,  and  are  in  fact  the  fibres  of  the  stem. 
They  give  strength  and  solidity  to  the  stem. 

Herbaceous  stems  have  but  little  wood  in  them,  and 
are  of  soft  texture,  dying  down  annually,  while  those  of 
shrubs  and  trees  (arborescent)  are  woody,  and  seem  to 
differ  mainly  in  the  size  and  height. 

14.  Endogenous  Stems, 

Endogenous  stems  have  no  distinct  outer  bark  that 
may  be  stripped  off,  and  no  central  pith  of  cell  tissue  free 
from  vascular  chords.  They  are  covered  with  a  skin  or 
epidermis  composed  of  layers  of  flattened  cells.  The  fibres 
grow  toward  the  centre,  tlie  outer  fibres  being  older  and 
Larder  ;  liciice  the  name,  Avhich  signifies  inside  groiccr.  In 


EXOGENOUS  STEMS. 


27 


some  trees  of  this  tribe,  as  the  palm,  the  outer  portion 
becomes  so  hard  as  to  admit  of  no  further  expansion,  and 
it  elongates  simply,  or  dies  from  the  choking  up  of  the 
central  fibres.  In  herbs,  however,  the  soft  stem  admits 
of  indefinite  growth. 

The  rushes  have  a  central  pith  composed  entirely  of 
cell  tissue,  while  the  reeds  and  grasses  are  hollow.  In  the 
maize,  the  bast  and  wood  cells  are  the  same  in  appear- 
ance. In  most  plants  they  difier ;  the  bast  cells  occupy- 
ing the  exterior  and  the  wood  cells  the  interior  of  the 
plant. 

Between  the  cells  is  a  delicate  tissue  called  the  cam- 
hiiim.  It  is  constituted  of  a  number  of  newly  formed 
cylindrical  cells  of  delicate  tissue.  It  exists  only  during 
the  growth  of  the  vascular  bundles  which  it  forms.  It 
then  grows  away  from  it  to  form  another. 

In  a  corn  stalk  the  cellular  tissue  is  the  first  to  rot, 
leaving  the  vascular  bundles  unimpaired.  They  form  a 
plexus  or  network  at  each  node,  and  may  be  torn  oul  like 
strings.  In  cutting  across  one  of  these  stalks  the  ducts 
may  be  seen  permeating  the  whole  surface. 

15.  Exogenous  Stems, 

Exogenous  plants  are  outside  groicers^  their  stems  en- 
larging in  diameter  from  the  exterior.  Their  seeds  have 
two  cotyledons.  Most  forest  trees  belong  to  this  class. 
Of  agricultural  plants,  we  have  the  potato,  beet,  turnip, 
bean,  ]Dea,  clover,  flax,  etc. 

The  ducts  and  fibrils  of  cell  tissue  form  just  within  the 
epidermis.  They  are  not  scattered  as  in  the  endogens, 
but  form  a  circle. 

The  structure  of  the  root  being  similar  to  the  stem,  a 
beet  root  cut  across  afi*ords  a  fine  example  of  the  concentric 
layers  of  vascular  tissue. 

The  pith  is  the  centre  of  the  stem.  In  young  and 
growing  stems,  it  is  full  of  juices  ;  in  old  ones  it  becomes 


28 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


dead  and  sapless.  The  pith  cells  are  filled  with  starch  in 
potato  tubers. 

The  Rind  is  occupied  with  cells  of  unusual  length, 
termed  bast  cells.  These,  with  their  ducts,  form  the  bast 
fibres  which  grow  on  the  interior  of  the  rind  next  to  the 
wood.  The  rind,  by  age  and  development  of  these  fibres, 
becomes  harh  in  trees  ;  which  gets  its  peculiar  toughness 
from  the  bast  cells.  All  textile  materials,  as  flax,  hemp,  etc., 
except  cotton,  are  bast  fibres.  The  external  bark,  as  in  fo- 
rest trees,  becomes  dead  and  sapless  from  age  and  falls  away. 

Cork  is  a  peculiar  formation  of  the  epidermal  cells  on 
the  cork  oak,  potato  tuber,  and  other  plants. 

Pith  rays  are  cells  which  interpose  between  the  fibres 
and  connect  the  pith  with  the  rind.  In  the  oak  and  maple 
they  are  known  as  silver  grains.  They  are  also  termed 
medullary  rays. 

The  camhimn  of  the  exogens  exists  between  the  bark 
and  wood,  from  which  wood  and  bast  fibres  develop.  In 
spring-time  the  new  cells  of  the  cambium  are  very  delicate 
and  easily  broken,  hence  the  bark  may  be  stripped  from 
the  w^ood  without  difficulty. 

The  sieve  cells^  which  originate  from  the  cambium,  and 
constitute  an  independent  set  of  ducts,  act  in  transmitting 
the  nutritive  juices  of  the  growing  plant.  These  cells  are 
extremely  delicate,  their  transverse  walls  perforated  like  a 
sieve,  so  as  to  communicate  with  each  other.  It  is  be- 
lieved that  the  nutriment  organized  in  the  leaves  passes 
downward  through  these  ducts,  to  supply  the  stems  and 
even  roots  with  food. 

3Iilk  ducts  also  exist  in  the  sweet  potato,  dandelion, 
milkweed,  etc.,  through  which  flow  milky  juices  to  nourish 
these  plants. 

The  water  w^hich  comes  from  the  cambial  ducts  sup- 
plies the  interior  of  the  leaf,  and  the  surplus  passes  out  of 
the  thickened  walls  of  the  epidermal  cells.  Their  cavities, 
however,  are  chiefly  filled  with  air.    A  smaller  portion  of 


OFFICES  OF  THE  STEM. 


29 


vajDor  passes  directly  through  the  stomata,  which  seem  to 
regulate  exhalation  to  a  large  extent,  by  closing  up  when 
rapid  evaporation  takes  place  in  dry  weather.  Thus  they 
prevent  too  rapid  a  loss  of  water  to  the  plant,  and  thereby 
save  it  from  perishing  till  perchance  the  rain  comes. 

While  there  are  new  cells  only  in  the  cambium,  the 
alburnum  or  sap  Avood  adjoining  carries  on  the  living 
processes  with  much  activity,  constituting  a  vehicle  for  the 
flow  of  the  nourishing  juices  of  the  plant. 

The  heart  wood  does,  not  fulfil  any  office  of  this  kind, 
but  receives  depositions  of  sap  through  these  channels, 
thereby  becoming  more  compact,  dense,  and  durable,  and 
better  fitted  for  industrial  purposes. 

A  striking  example  between  the  alburnum  and  heart 
wood  is  seen  in  the  pine.  The  sap  rotting  away  and  leav- 
ing the  heart  or  light  wood  standing  for  many  years.  This 
durability  is  owing  to  the  cells  being  filled  with  resin  so 
as  to  make  the  wood  impermeable  to  water. 

The  herbaceous  stems  of  exogenous  annual  plants,  usual- 
ly have  but  one  ring  of  woody  tissue,  with  a  central  pith 
and  external  bark. 

The  woody  stems  of  perennial  exogens  of  temperate 
zones  have  a  series  of  rings,  equal  to  the  number  of  years 
of  their  growth.  This  is  owing  to  the  finer  woody  cells 
formed  in  autumn,  at  the  cessation  of  growth,  being  more 
compact  than  the  larger  and  more  vigorous  cells  of  spring- 
time, by  which  a  distinct  mark  is  made,  easily  perceptible 
to  the  eye  in  the  oak  and  other  trees. 

The  cone-bearing  trees,  as  pines  and  firs,  have  no  ducts, 
but  visible  pores  to  answer  the  purpose  of  sap  and  air  chan- 
nels, through  which  different  cells  communicate  laterally, 
their  contents  passing  directly  from  one  to  another. 

16.   Offices  of  the  Stem. 
The  stem  bears  the  leaves,  flowers,  and  seeds  of  the 


so 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


plant.  Some  plants,  as  the  cacti,  have  no  leaves,  the  stems 
jDerforming  their  office. 

The  stem  conveys  nourishment  to  the  leaves  and  flow- 
ers, and  supports  them  mechanically,  and  acts  as  a  vehicle 
for  the  ascending  sap  from  the  soil,  and  the  descending, 
gathered  in  part  from  the  atmosphere  to  sustain  the  plant. 

The  stem  forms  the  principal  part  of  forest  trees  by 
weight,  subserving  important  purposes  for  fencing,  fire- 
wood, lumber,  etc. 


OHAPTEE  Y. 

OF  THE  LEAVES.  THEIR  OFFICES.  STOMATA.  BUDS. 

1 7.    Of  the  Leaves. 

The  Leaves  of  plants  issue  from  the  stems  and  limbs, 
and  spread  out  a  broad  thin  membrane  (the  Blade),  so  as 
to  present  an  extensive  surface  to  sunshine  and  air.  This 
membrane  is  connected  with  a  network  of  ducts  and  fibres. 
It  seems  to  be  an  expansion  of  the  cambium  of  the  stem. 
The  veins  or  ribs  are  a  continuation  of  the  vascular  bun- 
dles of  the  stem. 

Leaves  are  covered  on  both  sides  with  an  epidermis,  ; 
which  has  thick-walled  cells,  generally  devoid  of  liquid.  I 
In  some  cases,  as  in  the  nettle,  it  has  hairs  or  glands  filled 
with  an  acid  liquid.  | 

The  stems  and  leaves  of  the  grasses  difier  but  little  in  t 
structure,  though  easily  distinguishable  from  each  other,  t 
In  trees,  however,  the  difierence  is  very  striking. 

The  leaves  of  plants  are  essential  to  the  vitality  of  roots  i 
except  during  winter,  in  the  case  of  deciduous  trees.  1 

Some  few  plants,  as  the  prickly  pear  (cactus),  have  no 
leaves. 

While  the  structure  of  leaves  is  very  diverse,  their  in- 
ternal arrangement  is  quite  simple.    The  active  cells  con- 


THE  STOMATA. 


31 


tain  all  the  principles  of  plants — also  the  chlorophyl  or 
leaf  green.    Other  cells  and  interspaces  contain  air  simpl}-. 

Leaves  of  sandy  soils  in  warm  climates  have  several 
layers  of  cell  walls,  which  are  also  quite  thick.  Nearly  all 
vigorous  leaves  have  some  shade  of  green.  This  is  true  of 
young  stems,  also  showing  their  close  relation  to  each  other. 

When  leaves  of  deciduous  trees  mature  in  autumn, 
they  gradually  lose  their  green  color  and  drop  off.  A  few 
plants,  mostly  cultivated  by  florists  for  this  peculiarity, 
have  leaves  of  white,  brown,  and  red  tints.  Their  cells, 
however,  contain  chlorophyl,  though  its  peculiar  green 
tint  is  masked  by  other  colors. 

18.   Offices  of  Foliage, 

The  main  office  of  the  leaves  is  to  put  the  plant  in  com- 
munication with  air  and  sunshine.  They  regulate  the 
escape  of  water,  which  enters  by  the  roots,  charged  with 
organic  and  inorganic  food  for  the  plant,  and  absorb  from 
the  air,  gases  which  supply  a  considerable  part  of  the 
nourishment  of  the  plant.  They  are  quite  as  essential  to 
the  building  up  the  vegetable  organism  as  the  roots. 

19.    Of  the  Stomata, 

All  plants  have  pores  or  mouths  called  Stomata^  by 
which  they  inhale  carbonic  acid  gas  and  exhale  water  and 
oxygen.  Hence  they  are  called  hreathing  pores.  They 
exist  mostly  on  the  under  surface  of  ordinary  leaves. 

Each  stoma  has  two  curved  cells,  with  an  opening  be- 
tween them.  This  orifice  undergoes  frequent  changes.  In 
damp  weather  they  curve  outward  and  the  orifice  enlarges. 
In  dry  air  they  straighten  up  and  it  is  nearly  closed.  In 
strong  light  they  are  also  enlarged,  which  is  one  reason 
why  sunlight  is  so  beneficial  to  plants. 
^  In  aquatic  plants,  the  stomata  are  wanting  in  all  leaves 
^  except  those  which  float  ;  the  surface  exposed  to  the  air 
only  having  them.    They  arc  very  sparse  on  the  upper 


32 


ANATOMY  AXD  PHYSIOLOGY  OF  PLANTS. 


leaves  of  land  plants,  but  numerous  on  the  lower  surface. 
In  plants  occupying  damp  and  shady  situations,  they  are 
more  numerous  and  occur  on  both  sides. 

The  stomata  are  very  variable  in  number,  some  leaves 
having  not  more  than  eight  hundred  to  the  square  inch  of 
surface,  while  others  have  one  hundred  and  seventy  thou- 
sand. 

There  are  twenty-four  thousand  mouths  on  the  under 
surface  of  every  square  inch  of  the  apple  leaf;  on  the  plum 
and  cherry  about  ninety  thousand,  on  the  vine  leaf  thirteen 
thousand  six  hundred,  on  the  yucca  (Adam's  needle)  forty 
thousand,  and  on  the  misletoe  only  four  hundred.  (Darby.) 

The  leaves  of  all  plants  during  their  healthy  existence 
are  constantly  absorbing  or  exhaling  gaseous  substances 
through  their  stomata.  These  connect  with  spaces  between 
the  cells,  which  are  generally  filled  with  air,  and  the  ducts 
continue  from  them,  ramifying  throughout  the  veins,  ter- 
minating in  the  vascular  bundles  of  the  stem.  There  are 
cracks  or  pores  in  the  bark  or  woody  stems,  through  which 
the  air  communicates  with  the  longitudinal  ducts. 

These  facts  were  demonstrated  by  Sachs  with  a  simple 
apparatus,  by  which  the  pressure  of  a  column  of  mercury 
forced  the  water  through  the  stomata  of  the  leaf,  the  inter- 
cellular spaces,  veins,  and  ducts,  into  the  ducts  of  the  leaf 
stem,  where  it  escaped  in  minute  bubbles. 

A  simple  demonstration  of  the  air  passage  may  be  made 
by  taking  a  section  of  a  corn  stalk:  immerse  one  end  in 
water  and  blow  through  the  other,  and  small  bubbles  of 
escaping  air  will  be  seen  on  its  surface. 

20.    Of  Buds, 

Buds  are  undeveloped  leaves  and  stems.  Leafhuds 
have  embyro  leaves  folded  into  each  other,  all  united  at 
the  base,  which  is  the  tip  of  the  stem.  The  flovm^  hud  is 
similar  in  structure,  only  the  embryo  fruit  may  be  seen  in 
many  buds  on  cutting  them  open. 


THE  FLOWER. 


33 


Trees  have  latent  hicds^  which  form  and  lie  dormant  till 
the  succeeding  summer,  unless  the  active  buds  have  been 
destroyed  by  frost  or  pruned  by  the  gardener.  Adven- 
titious buds  also  spring  out  from  the  bark  where  there  are 
no  latent  buds,  when  trees  are  cut  down,  as  is  seen  in  the 
maple  and  chestnut. 

Flower  buds  prepare  for  the  reproductive  organs.  They 
resemble  the  leaf  buds  at  first,  but  later,  are  larger  in  size 
and  dilFer  in  shape  and  color. 


CHAPTEK  YL 

OF  THE  KEPRODUCTIVE  ORGANS. — FLOWERS.  FRUIT,  SEED. 

21.  TheFloxoer. 

BoTAis^iCALLY  Speaking,  the  flower  has  four  difierent 
sets  of  organs,  the  Calyx,  Corolla,  Stamens,  and  Pistils. 

The  calyx  or  cup  is  the  outermost  envelope  of  the 
flower.  It  is  sometimes  red  or  white,  but  generally  green. 
Its  leaves  are  called  sejmls. 

The  corolla  or  crown  is  one  leaf,  or  may  be  composed 
of  several  small  leaves  within  the  calyx,  called  petals. 

The  stamens  are  thread-like  organs  which  emerge  from 
within  the  corolla  ;  they  are  terminated  by  an  oblong  sack, 
called  the  anther.  This  latter  encloses  the  pollen,  a  fine 
brown  or  yellow  dust,  which  has  an  important  ofiice  to  fill. 

The  pistil  or  pistils  emerge  from  the  centre  of  the 
flower  ;  they  vary  in  form,  having  the  seed  vessels,  or 
ovaries,  at  their  base.  The  ovides  (little  eggs),  which  are 
the  rudimentary  seeds,  occupy  the  ovaries.  The  end  of 
the  pistil  has  no  skin  or  epidermis  upon  it,  and  is  called 
the  stigma. 

In  some  plants,  termed  7nonoerious,  the  stamens  and 
2* 


34 


ANATOMY  AKD  PHYSIOLOGY  OF  PLATs^TS. 


pistils  are  in  separate  flowers,  as  the  oak  and  birch  trees, 
Indian  corn,  melon,  squash,  cucumber,  and  straAvberry. 

In  maize,  the  tassels  are  the  staminate,  and  the  silk  the 
pistillate  flowers.  Every  fibre  of  the  silk  has  an  ovary  at 
its  base,  which  develops  to  a  grain  when  impregnated  by 
the  pollen  from  the  tassel. 

The  staminate  are  called  the  male  or  sterile,  the  pistil- 
late the  female  or  fertile  flow^er. 

Dioecious  plants  have  the  male  and  female  in  separate 
individuals,  as  the  willow,  persimmon,  hemp,  and  hop  vine. 

22.  Fructification, 

Fructification  is  the  grand  function  of  reproduction 
in  flowers.  In  order  to  this  the  pollen  must  touch  the 
naked  tip  of  the  pistil.  Here  it  sends  out  a  slender  tube, 
seen  under  the  microscope  down  in  the  interior  of  the  pis- 
til, till  it  reaches  the  seed  sack  and  touches  the  ovule,  which 
becomes  fertilized,  and  begins  to  grow.  The  corolla  and 
stamens  now  gradually  wither,  and  the  ovules  increase  in 
size  until  the  seeds  are  ripe. 

The  pollen  is  carried  by  winds  or  insects  to  pistillate 
plants,  and  seem  to  be  quite  sufiicient  in  every  case,  as 
artificial  fecundation  has  not  seemed  to  be  of  any  special 
advantage. 

It  is  believed  that  the  wheat  crop  sometimes  fails  from 
the  pollen  being  washed  ofl*  by  heavy  rains.  This  is  pro- 
bably true,  as  much  rain  about  the  blooming  of  wheat 
seems  to  lighten  the  crop. 

23.  Of  the  Fruit. 

The  Fruit  succeeds  the  flower.  The  ovary  becomes  the 
pericarp,  or  seed  vessel,  and  the  ovules  become  the  seeds. 

Stone  fruity  or  Drupe,  is  a  nut  enveloped  by  a  fleshy 
coat,  as  the  peach,  cherry,  and  hickory  nut.  Blackberries, 
raspberries,  etc.,  are  clusters  of  small  drupes. 

Dome  is  a  term  npiJied  to  such  fruits  as  the  apple, 


THE  SEED. 


35 


pear,  etc.,  the  coi'e  being  the  true  seed  vessel,  and  the 
tiesh)^  edible  part  constituting  a  thickened  calyx. 

A  Berry  is  a  many-seeded  fruit,  as  the  grape,  tomato, 
huckleberry,  etc. 

The  Kilt  has  a  hard  or  leathery  shell,  as  the  acorn, 
chestnut,  hazelnut,  etc. 

Gourd  fruits  have  a  hardened  rind  and  soft  fleshy  in- 
terior, as  the  melon,  squash,  cucumber,  etc. 

Pods  are  dry  seed  vessels,  which  open  and  scatter  their 
seeds  when  ripe,  as  the  touch-me-not. 

The  Legume  is  a  pod  which  splits  in  two  halves,  like 
the  bean  or  pea.  The  pulse  family  are  termed  legumi- 
nous, from  the  shape  of  their  fruit. 

Grains^  as  of  the  cereals,  are  properly  fruits,  of  which 
the  bran  is  the  seed  vessel. 

The  Akene  is  a  plant  with  a  single  seed  in  its  dry  en- 
velojje,  as  the  sunflov/er. 

24.    Of  the  Seed, 

The  Seed  properly  consists  of  its  coats  and  its  kernel. 
It  has  generally  two  coats.  In  the  cotton  seed  the  fibre 
seems  to  answer  for  the  outer  and  the  hull  for  the  inner 
coat. 

The  Kernel  lies  within,  and  consists  of  the  embryo  and 
endosperm  or  cdhumen. 

The  Embryo  is  the  chit  or  germ  of  the  plant,  having 
root,  stem,  leaves,  and  bud  in  a  state  of  incipient  develop- 
ment. It  contains  the  radicle,  the  plumule,  and  the 
cotyledon. 

By  soaking  a  grain  of  corn  for  a  few  days  in  water,  the 
embryo  can  be  easily  separated  from  the  endosperm,  and 
all  three  of  its  parts  plainly  exhibited. 

The  liadicle  is  tlie  rootlet  or  point  from  which  the  root 
\  starts  downward. 

,       The  Plumade  is  the  central  bud  from  which  the  stem  is 
developed. 


36  ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


The  Cotyledon  is  the  leaf-like  structure  which  clasps  the 
plumule  in  the  embryo,  and  appears  above  ground  as  the 
first  leaves  in  many  plants. 

Endogenous  plants  have  but  one  cotyledon,  while  the 
exogens  have  two. 

The  pine,  and  others  of  its  species,  have  often  five  or  ten 
small  cotyledons  arranged  in  a  circle  ;  they  are  called 
polycotyledonous. 

In  some  plants,  as  the  horse  bean  and  pea,  the  cotyle- 
dons never  form  leaves,  but  remain  in  the  soil,  decay,  and 
feed  the  young  plant.  The  seeds  of  nearly  all  agricultural 
plants  of  this  class  have  no  endosperm,  such  as  the  legu- 
minosa,  crucifera,  and  ordinary  fruits;  also  the  gourd 
family  and  some  trees,  as  the  oak,  elm,  maple,  etc. 

The  embryo  of  the  seed,  after  its  maturity,  kept  in  a 
dry  state,  lies  dormant,  losing  its  vitality  at  various  peri- 
ods. Willow  seed,  for  instance,  will  not  germinate  longer 
than  two  weeks  after  maturing.  Of  agricultural  j^lants, 
the  leguminous  seeds  remain  uninjured  for  a  long  period. 
Girardin,  it  is  said,  sprouted  beans  over  a  century  old  ; 
and  Grimstone  produced  peas  from  a  seed  taken  from  a 
sealed  vase  of  an  Egyptian  sarcophagus  believed  to  be 
nearly  3,000  years  old. 

Coffee  berries  lose  their  germinating  powers  more 
rapidly  than  most  other  seeds  ;  hence  it  is  very  difiicult  to 
get  them  to  germinate  after  they  are  transj)orted  to  this 
country.  They  should  be  planted  as  soon  as  taken  from  the 
bush.  Yet  it  is  remarkable  that  when  steeped  in  a  weak 
solution  of  carbonate  of  ammonia,  or  sal  ammoniac,  their 
vitality  seems  to  return,  and  many  of  them  will  sprout 
readily. 

Doubtless  seeds  kept  free  from  exposure  to  atmospheric 
vicissitudes,  especially  moisture,  may  be  kept  for  centuries. 
In  agriculture,  as  a  general  rule,  new  seeds  are  the  best, 
though  some  practical  planters  think  otherwise. 

Loudet  experimented  with  wheat  one,  two,  and  three 


THE  SEED. 


37 


years  old.  One  hundred  seeds,  one  year  old,  produced 
404  heads.  Those  two  years  old,  365  heads  ;  and  three 
years  old,  269  heads. 

Haberlandt  found  that  eight  per  cent,  of  wheat  seed 
germinated  which  were  six  years  old,  but  none  older. 
Barley  twenty-four  per  cent,  six  years  old  ;  oats  sixty  per 
cent,  eight  years  old ;  and  maize  seventy-six  per  cent,  six 
years  old.  Of  seeds  two  years  old,  100  of  maize  germi- 
nated, eighty  of  oats,  ninety-two  of  barley,  forty-eight  of 
rye,  eighty-four  of  wheat.  Rye  failed  entirely  the  third  year. 

Melon  seeds  kept  for  several  years  produce  more  fruit 
than  new  seeds,  which  are  more  disposed  to  run  to  vine. 
Old  flower  seeds  produce  weak  plants,  but  better  flowers, 
and  in  some  instances  double  flowers  have  been  produced 
by  seeds  several  years  old. 

Unripe  seed  of  cereals,  when  the  kernel  is  soft,  and  be- 
fore starch  is  formed,  will  germinate  in  some  instances, 
but  not  produce  as  good  a  crop,  especially  on  poor  land. 
Siegart  says  that  unripe  seeds  of  peas  will  produce  early 
varieties.  Some  flowers,  as  the  gilliflower,  will  also  pro- 
duce double  blossoms  from  the  unripe  shrivelled  seed. 

Experiments  of  Muller  and  HeHreigel  prove  that  light 
grains  will  sprout  quicker  than  full,  heavy  grains;  but  not 
germinate  as  surely,  and  produce  weaker  plants.  Practi- 
cal planters  have  found  this  out.  Some  of  them  throw 
their  seed  across  a  barn  floor,  and  gather  up  those  at  the 
extreme  end,  as  the  heaviest,  for  planting. 

Liebig  says  "  the  strength  and  number  of  the  roots  and 
leaves  formed  in  the  process  of  germination  (as  regards  the 
non-nitrogenous  constituents)  are  in  direct  proportion  to 
the  amount  of  starch  in  the  seed."  He  says  further  that 
"  poor  and  sickly  seeds  will  produce  stunted  plants,  which 
will  again  yield  seeds  bearing  in  a  great  measure  the  same 
character." 

Boussingault  says  that  seed  sown  in  sterile  soil  will 
produce  perfect  seed,  though  diminutive  ;  sown  in  a  fer- 


38 


AIS-ATOMY  AND  PHTSIOLOGY  OF  PLANTS. 


tile  soil,  these  seed  will  produce  plants  of  a  natural  size. 
Frof.  Church,  of  the  Royal  College  of  Cirencester,  Eng- 
land, made  a  number  of  experiments  in  1863-4  on  the 
germinating  qualities  of  wheat  seed,  particularly  as  to  their 
density.  He  came  to  the  following  conclusions  :  1.  Seed 
wheat  of  the  greatest  density  produced  the  densest  seed, 
and  yielded  the  greatest  amount  of  dressed  corn.  2.  Seed 
of  medium  density  produced  more  ears,  but  of  a  poorer 
quality,  and  also  the  largest  number  of  fruiting  plants. 
3.  Wheat  grains,  which  sink  in  water,  but  float  in  a  liquid 
(salt  water,  for  instance)  which  has  a  specific  gravity  of 
1.247,  are  of  very  low  value,  yielding  on  an  average  34.4  lbs. 
of  dressed  grain  for  every  100  yielded  by  the  densest  seed. 
Church  found  the  densest  not  always  the  largest  seed. 

From  the  above  facts  too  much  care  cannot  be  used  by 
farmers  in  the  selection  of  ripe,  healthy  seeds,  to  23revent 
depreciation  in  the  quality  and  quantity  of  farm  products. 
At  the  same  time,  Schubert  says  truly  that  "  the  vigor  of 
plants  depends  far  less  on  the  size  and  w^eight  of  the  seed 
than  upon  the  depth  to  which  it  is  covered  in  the  earth, 
and  the  stores  of  nourishment  which  it  finds  in  its  first 
period  of  life."  This  indicates  not  only  the  importance  of 
having  land  well  fertilized,  but  having  plenty  of  soluble 
food  for  the  crop  put  under  the  seed  to  give  the  plant  a 
vigorous  start. 


OHAPTEE  VIL 

PROCESSES  OF  PLANT  LIFE. 

25.  Germination  of  Seed. 

The  first  process  of  vegetable  life  is  germination.  It 
is  produced  in  agriculture  by  burying  the  seed  a  proper 
depth  in  the  earth,  thereby  securing  warmth,  moisture,  and 
uiodified  light. 


GERMIXATIOi^'  OF  SEED. 


39 


The  seed  first  absorbs  a  large  amount  of  water,  and 
swells  and  softens;  the  germ  enlarges  beneath  the  seed  coat, 
which  bursts,  and  the  radicle  first  appears,  pushing  down- 
ward in  the  soil;  and  next  the  plumule,  which  ascends, 
bursting  through  the  soil,  seeking  air  and  light.  The 
endosperm,  where  any  exists,  as  in  the  cereals,  remains  to 
nourish  the  plant;  as  does  the  cotyledon  in  some  instances, 
as  in  the  pea,  maize,  and  barley ;  while  in  others,  as  the 
buckwheat,  squash,  and  radish,  the  cotyledons  push  up 
with  the  plumule  forming  the  first  pair  of  leaves. 

The  radicle  of  the  seeds  goes  downward  into  the  soil, 
and  divides  and  subdivides  into  new  roots;  and  the  plu- 
mule, ascending  upward,  spreads  into  new  branches  and 
leaves,  and  thus  a  perfect  phant  is  formed. 

Seeds  require  heat,  moisture,  and  oxygen  gas  to  pro- 
duce germination.  Goeppert  found  that  no  seeds  would 
sprout  below  39^  F.  In  Sachs'  exj)eriments  some  sprouted 
at  41^,  others  required  55^.  Some  would  not  germinate 
at  a  higher  temperature  than  102^,  others  116^.  The 
vitality  of  the  seed  is  preserved  below  the  minimum  and 
killed  above  the  maximum.  The  point  of  rapid  germina- 
tion is  between  the  two  extremes,  70°  to  93°. 

The  following  table  presents  the  special  temperatures 
for  six  field  and  garden  plants  : 


Lowest. 

Highest. 

Most  rapid. 

Wheat 

 41^  F.. 

.  104^  F  . 

....84^  F. 

Barley 

....41  ... 

...104  .. 

,  .  ,84 

Pea  

 44.5... 

...102  .. 

,  ,  84 

.  ,,    48  ... 

...115  .. 

....93 

 49  ... 

...Ill  .. 

. ,..79 

 54  ... 

...115  .. 

....93 

Doubtless  plants  in  frigid  zones  will  germinate  much 
lower  (probably  near  the  freezing  point),  and  in  inter- 
tropical climates  much  higher.  The  cocoanut,  it  is  said, 
requires  a  soil  of  120°'F. 


40 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


Sachs  observed  that  the  temperature  of  seed  germina- 
tion has  much  to  do  with  the  health,  vigor,  and  product 
of  the  plant — low  temperature  retarding  the  growth  of 
the  root  buds  and  leaves,  while  high  temperature  makes 
them  too  rapid.    A  medium  is  the  best. 

While  a  proper  temperature  is  deemed  essential  for  the 
germination  of  plants,  Koppen  concludes,  from  experiments 
made,  that  variations  in  temperature  are  always  prejudicial 
to  the  growth  of  the  germ,  even  when  amounting  to  only  a 
few  degrees,  and  within  the  limits  favorable  to  energetic 
growth.  Thus  germination  proceeds  more  rapidly  at  a 
low  but  uniform  temperature  than  at  a  high  and  varia- 
ble temperature.  Cool  nights  and  warm  days  are  more 
unfavorable  than  cloudy  days  with  moderately  warm 
nights. 

Seeds  will  not  germinate  without  moisture,  and  even 
when  half  sprouted,  if  deprived  of  it,  the  process  ceases. 
The  absorption  of  water  puts  in  motion  the  contents  of  the 
germ  cells  by  expansion.  Excess  of  water  is,  however, 
injurious  to  land  plants,  causing  them  to  rot. 

Saussure  proved  that  free  oxygen,  as  contained  in  the 
atmosj^here,  was  also  essential  to  the  growth  of  the  embryo, 
being  excited  by  its  presence. 

Johnston  taught  that  light  was  opposed  to  germination. 
Prof.  S.  W.  Johnson  dissented.  He  says  that  "  the  seeds 
of  common  agricultural  plants  will  sprout  when  placed  on 
moist  sand  or  sawdust,  with  apparently  no  less  readiness 
than  wlien  buried  out  of  sight."  In  twenty-four  experi- 
ments, Hoffman  came  to  the  conclusion  that  light  had  no 
appreciable  influence  on  the  germination  of  seeds. 

The  time  of  germination  is  very  variable  with  different 
seeds.  Beech,  maple,  and  ash  require  one  or  two  years, 
while  several  weeks  is  all  required  by  the  pine,  walnut, 
and  larch.  The  willow  seed  will  sprout  in  12  hours  after 
it  strikes  the  ground.    Common  agricultuial  plants,  as 


PLANT  GROWTH. 


41 


corn,  cotton,  and  oats,  sprout  in  from  three  to  five  days. 
Seeds  in  thick,  hard  envelopes,  as  the  okra  and  beet,  re- 
quire much  longer  time  than  others.  Oily  seeds  are  slower 
than  thin-skinned  starchy  seeds. 

It  took  22  days  for  a  sugar  beet  to  sprout  at  a  tempera- 
ture of  41^  F.  (according  to  Haberlandt),  and  4  days  for 
rye.  The  time  was  shortened  one-half  at  a  temperature 
of  51^.  Indian  corn,  at  this  temperature,  sprouted  in  11 
days,  and  at  61"^  in  3  days. 

The  process  of  germination  lasts  from  the  time  the  root- 
let appears  until  the  seed  is  exhausted  of  its  nutriment. 
Smaller  seeds  will  germinate  sooner  than  larger  ones,  be- 
cause the  supply  of  nutriment  is  less. 

Covering  seed  in  the  soil  seems  to  be  only  essential  to 
supply  proper  warmth  and  moisture.  It  also  protects  from 
birds  and  freezing  out  in  the  winter.  Porous,  light  soils 
require  deeper  planting  than  close,  compact  soils. 

According  to  Prof.  Johnson,  the  Indians  of  Colorado 
plant  their  corn  at  a  depth  of  12  to  14  inches,  as  it  will  not 
sprout  in  their  dry  and  sandy  soils  nearer  the  surface,  for 
lack  of  moisture.  HolFman  found  no  seeds  to  sprout  at 
12  inches  on  light  loamy  land,  out  of  24  kinds  which  he 
tried.  At  10  inches,  none  but  peas,  vetches,  beans,  and 
maize  sprouted.  At  8,  besides  these,  wheat,  millet,  oats, 
barley,  and  colza.  At  6  inches,  buckwheat,  the  beet,  and 
winter  colza.  At  4,  besides  all  the  preceding,  mustard, 
red  and  white  clover,  flax,  horse-radish,  hemp,  and  turnips ; 
and  at  3  inches,  lucerne.  The  deep-planted  seed  sprouted 
1  first,  and  no  difierence  appeared  in  the  plants  from  deep 
and  shallow  planting  by  the  time  of  blooming. 

Gronven  found  difierent  results  on  a  difierent  soil.  The 
character  of  the  soil,  the  temperature,  the  relative  mois- 
ture will  require  difierent  depths  ;  hence  no  general  rule 
'  can  be  laid  down. 


• 


42  ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 

26.  Plant  Groioth, 

All  plants  possess  in  common  so  many  features  of  resem- 
blance, that  a  complete  study  of  one  gives  a  very  good 
knowledge  of  the  whole.  Difierences  are  rather  incidental 
than  radical,  either  as  to  their  structure  or  functions. 

In  all  seeds  the  plantlet  exists  in  one  form  or  another 
before  germination  begins. 

The  stem  seeks  the  light,  the  root  avoids  it.  Why,  we 
cannot  tell. 

They  grow  in  opposite  directions  ;  the  stem  upward, 
the  root  downward.  They  also  grow  in  a  different  way. 
The  stem  produces  joints,  each  growing  upon  the  summit 
of  its  predecessor,  and  elongating,  as  the  stem  lengthens, 
until  the  plant  is  fully  grown,  each  bearing  one  or  more 
leaves  on  its  summit.  The  root  has  no  joints  or  nodes, 
and  lengthens  only  from  its  extremity.  The  stem  has  a 
length  to  begin  with  in  the  embryo  ;  the  root  has  none, 
but  begins  a  new  formation  at  the  base  of  the  stemlet,  and 
lengthens  by  accretion,  the  parts  formed  not  elongating 
afterward.  But  for  this  wise  arrangement  the  lateral 
roots  would  be  broken,  as  their  fibrils  would  branch  out 
and  become  attached  to  the  solid  earth,  and  their  base  be 
drawn  forward  in  the  process  of  elongation  after  the  parent 
root. 

Traube  proved  the  elongation  of  the  stem  by  fastening 
the  cotyledons  of  a  young  pea  plant  to  a  rod,  the  stem  and 
rod  both  being  marked  at  equal  intervals  with  a  mixture 
of  indigo  and  oil.  The  spaces  on  the  stem  widened  be- 
tween the  lines,  w^hich,  when  compared  with  those  on  the 
rod,  showed  that  no  growth  took  place  at  the  distance  of 
near  an  inch  from  the  base  of  the  terminal  bud. 

27.  Nutrition  of  the  Plantlet, 
The  nourishment  of  the  germinating  plantlet  is  pro- 
vided beforehand  by  the  parent  plant,  and  stored  up  either 


NUTRITION  OF  THE  PLANTLET. 


43 


ill  or  around  the  embryo.  There  is  just  enough  of  this  to 
begin  the  root,  and  push  it  out  in  the  soil  to  seek  more, 
and  to  bring  up  the  seed  leaves  to  the  surface,  where  they 
may  unfold  and  begin  to  absorb  nutriment  from  the  air. 
Hence  if  the  seed  is  planted  so  deep  as  that  the  food  gives 
out  before  the  stem  reaches  the  light,  the  planllet  dies. 

In  some  cases,  however,  a  larger  supply  of  nourishment 
is  provided,  and  the  plant  is  not  thrown  upon  its  own  re- 
sources quite  so  early,  as  in  the  pea  and  the  horse-chestnut. 
The  squash  or  pumpkin  has  scarcely  anything  but  the  two 
seed  hairs  within,  but  yet  they  are  themselves  very  rich  in 
food,  which  causes  them  to  grow  rapidly  and  have  very- 
long  stems  before  leafing.  And  so  of  the  peach,  almond, 
and  plum.  In  other  cases  the  food  is  deposited  outside  of 
the  embryo,  a  good  example  of  which  is  the  convolvulus, 
or  morning  glory. 

This  store  of  food  thus  deposited  around  the  germ  was 
first  called  albumen,  a  name  which  it  still  retains  from  its 
resemblance  to  the  white  of  the  egg  enclosing  the  yolk. 

Plants  sometimes  lay  up  their  food  in  underground 
stems,  as  the  artichoke  and  Irish  potato.  These  thickened 
ends  are  called  tubers.    They  are  not  roots. 

In  some  cases,  as  the  house-leek,  the  nourishment  for 
the  next  year's  growth  is  laid  up  in  the  leaves. 

In  shrubs  and  trees,  much  of  the  nutritive  substance 
made  the  previous  summer  is  preserved  in  the  young  wood, 
bark  of  the  shoots,  trunk,  and  roots,  for  them  to  feed  on  the 
next  spring.  By  this  means  they  shoot  forth  vigorously, 
and  clothe  the  forests  in  rich  foliage  in  a  few  days. 


44 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


CHAPTER  VIII. 

PEOCESSES  OF  PLANT  LIFE — (CONTINUED.) 

28.  Formation  and  Groioth  of  Wood. 

The  theory  of  the  French  botanists,  in  reference  to  the 
formation  and  growth  of  wood,  is  tliat  it  begins  in  the 
leaves  or  leaf  buds,  and  descends  continuously  to  the 
roots,  so  that  the  united  mass  of  wood  in  the  stems  and 
roots  emanate  from  the  leaves  of  the  plants. 

An  objection  to  this  theory,  however,  is  found  in  the 
fact  that  the  stumps  of  pines  and  other  coniferous  trees 
often  increase  in  diameter,  forming  new  woody  layers  for 
several  years.  Dutrochet  mentions  the  instance  of  a  stump 
of  a  Pinus  picea,  wdiich  was  felled  in  1821,  being  still  alive 
in  1836,  having  fourteen  new  thin  layers  of  wood  ;  and  one 
felled  in  1743  was  still  alive,  having  formed  ninety-two 
thin  layers  of  w^ood ;  one  for  each  year. 

-  Goeppert  investigated  this  subject  as  early  as  184-3,  and 
found  a  union  of  the  roots  of  the  fallen  trees  with  the  roots 
of  living  trees,  growing  in  the  immediate  vicinity  ;  yet 
this  does  not  explain  why  the  sap,  which  is  thus  robbed 
from  the  roots  of  living  trees,  in  passing  up  the  usual 
channels,  does  not  overiiovv^  tlie  top  of  the  stump,  as  in  the 
case  of  a  grape  vine  or  a  deciduous  tree,  when  cut  during 
the  ascent  of  the  sap.  And  as  the  growth  of  new  wood  in 
exogenous  trees  is  from  the  cambium,  and  the  theory  makes 
the  cambium  the  sap,  which  has  been  elaborated  in  the 
leaves,  from  w^hence  does  the  cambium  of  these  stumps 
originate  ? 

These  facts  certainly  prove,  if  they  prove  anything, 
that  wood  formation  is  independent  of  the  descending  sap 
elaborated  in  the  leaves,  at  least  under  certain  circum- 
Btances;  and  that  vegetable  physiologists  must  look  further 


CUARACTER  AND  DURATION  OF  PLANTS. 


45 


than  the  theory  of  the  French  botanists  for  an  explanation 
of  this  subject. 

The  vegetable  cells  constitute  the  formative  state  of  all 
the  tissues  of  the  plant,  each  of  which  may  be  considered 
an  independent  body.  The  extension  of  the  wood  of  the 
tree  in  any  direction  is  through  the  cell  growth ;  and  where- 
ever  the  cellular  tissue  is  in  a  state  of  vitality,  and  the 
sap  is  brought  in  contact  with  it  from  whatever  source, 
there  will  be  cell  multiplication  and  material  growth. 

29.    Character  and  Duration  of  Plants. 

Plants  are  divided  into  Herbs,  Shrubs,  and  Trees.  The 
first  class  are  short-lived,  some  existing  only  for  a  few 
weeks;  while  trees  are  known  to  endure  for  centuries. 

Herbs  are  Annual,  Biennial,  and  Perennial. 

Annuals  generally  come  up  from  the  seed  in  the  spring, 
and  die  in  the  autumn. 

Our  common  agriculturial  plants,  corn,  cotton,  and 
peas,  are  familiar  examples.  Some,  as  wheat,  oats,  and 
barley,  spring  up  in  the  fall,  and  mature  and  die  in  the 
early  summer. 

Biennials  live  for  two  years,  bloom  the  second  year, 
and  die  when  they  ripen  their  seeds.  The  turnip,  carrot, 
and  beet  are  examples.  They  have  a  bud  on  their  roots, 
which  is  an  embryo  stem,  in  which  nourishment  is  depos- 
ited for  the  next  season's  growth.  When  this  bud  is  cut 
out  the  roots  may  continue  to  grow,  but  the  prospective 
stem  is  destroyed. 

Perennials  are  ever-living  plants,  to  which  class  belong 
all  shrubs  and  trees  and  many  herbs.  Perennial  herbs, 
however,  generally  die  down  to  the  ground  on  the  approach 
of  winter. 

Climate  has  much  to  do  with  the  character  and  dura- 
tion of  plants.  The  cotton  plant,  for  instance,  is  an  annual 
here,  but  in  Central  America  assumes  the  character  of  a 


46 


ANATOMY  AXD  PHYSIOLOGY  OF  PLANTS. 


shrub  or  small  tree.  We  occasionally  see  it  even  here 
live  through  a  mild  winter,  and  ratoon  the  next  spring  from 
the  living  roots,  and  rarer  from  the  stems. 


CHAPTER  IX. 

CIRCULATION  OF  FLUIDS  IN  PLANTS. 

30.  Absorption  of  Water, 

Formerly  it  was  supposed  that  plants  had  the  power 
to  absorb  vapor  of  water  as  well  as  to  imbibe  liquid  water 
from  the  atmosphere.  This  theory,  however,  has  been  ex- 
ploded. Duchartre  found  that  when  plants  were  excluded 
from  the  air,  and  their  roots  allowed  to  receive  moisture, 
they  increased  rapidly  in  weight  ;  while  they  lost  in  air 
nearly  as  possible  saturated  with  water,  where  the  roots 
were  excluded  from  it.  Sachs  established,  by  a  number  of 
interesting  experiments,  that  even  the  roots  are  incapable 
of  taking  watery  vapor. 

More  recently,  M.  Cailletet  has  found  that  while  the 
leaves  of  plants  neither  absorb  water  nor  vapor  of  water, 
when  there  is  a  sufficient  supply  of  water  in  the  soil  to  fur- 
nish the  roots,  yet  when  there  is  a  deficiency  of  this  im- 
portant principle,  the  leaves  do  absorb  liquid  water,  but 
under  no  circumstances  do  they  imbibe  watery  vapor. 

This  explains  the  fact  that  certain  plants  are  able  to 
maintain  a  healthy  condition  without  any  contact  w^ith  the 
soil,  as  in  the  case  of  water  culture. 

The  absorptive  force  by  which  roots  imbibe  water  is 
very  great.  Hales,  who  experimented  one  hundred  and 
forty  years  ago  with  a  grape  vine,  found  in  one  instance 
that  the  pressure  was  equal  to  the  support  of  a  column  of 
mercury  32^  inches  high,  equal  to  36|-  feet  of  water.  Hof- 


ABSOEPTION   OF  WATEK. 


47 


meister  made  the  force  of  the  vine  29  inches,  a  beau  7 
inches,  and  nettle  14.  This  power  resides  in  the  surface 
of  the  young  roots,  and  is  greater  the  less  the  length  of 
the  stem  (Dutrochet) ;  a  long  stem  resisting  the  rise  of  the 
liquid  more  than  a  short  one.  The  seat  of  the  absorbing 
power  is  near  the  extremities,  but  not  at  them.  (Ohlerts.) 
The  absorbent  force  is  more  vigorous  when  the  rootlets  are 
in  active  development. 

The  forcible  imbibition  of  water  into  plants  sometimes 
causes  its  exudation  on  its  foliage.  Instance,  a  drop  of 
water  on  the  tip  of  the  leaves  of  young  corn.  Also,  the 
bleeding  of  the  grape  vine  when  severed  while  young. 
The  stumps  of  large  trees  when  cut  down  in  spring-time 
are  often  full  of  water  exuding  from  the  cut  surface. 

The  amount  of  water  taken  up  by  the  roots  is  increased 
by  an  elevated  temperature  and  decreased  by  a  low  tem- 
perature in  the  soil.  Sachs  observed  an  entire  cessation 
of  absorption  when  the  temperature  was  reduced  to  41^ 
F.  On  a  morning  in  November,  when  the  thermometer 
had  fallen  to  this  point,  he  observed  that  some  tobacco 
and  squash  plants  in  his  room  (which  were  growing  in  a 
soil  nearly  saturated  with  water),  hung  down  their  leaves 
like  wet  cloths,  as  if  wilted  by  the  heat  of  the  sun.  On 
Avarming  the  soil,  the  leaves  returned  to  their  natural  tur- 
gidity.  He  found  by  further  experiments,  that  plants 
would  wilt  in  a  few  hours  by  surrounding  them  with  snow, 
showing  that  a  cold  soil  would  so  contract  the  roots  as  to 
completely  prevent  absorption.  Pie  also  found  that  certain 
salts  added  to  a  soil,  as  phosphate  and  silicate  of  potash, 
sulphates  of  lime  and  magnesia,  would  produce  the  same 
effect,  retarding  the  transpiration  from  10  to  90  per  cent., 
while  a  diluted  solution  of  free  nitric  acid  would  accelerate 
it  correspondingly. 

Boehm  has  come  to  the  conclusion,  from  recent  experi- 
ments, that  transpiration  of  water  through  plants  actually 


48 


ANATOMY   AND  PHYSIOLOGY  OF  PLAKTS. 


ceases  when  the  surrounding  atmosi^liere  is  saturated  with 
watery  vapor.  So  that  tlie  dryness  of  air  has  much  to  do 
with  this  process.  Hesse  found  that  a  beet  leaf,  gathered 
at  evening,  after  several  days  of  dry  sunshiny  weather,  con- 
tained 85.74  per  cent,  of  water,  while  a  similar  one,  pulled 
the  next  morning  after  a  heavy  rain,  yielded  89.57  per  cent. 
The  difference  of  3.8  per  cent,  between  the  two  leaves 
(which  other  observations  corroborated),  shows  clearly 
that  the  wilting  in  dry  weather  is  caused  by  a  more  rapid 
exhalation  than  absorption  of  w^ater  by  plants. 

The  absorptive  power  of  plants  is  weakened  by  cold 
and  increased  by  w^armth.  At  41^  F.,  Sachs  found  it  to 
cease  in  the  squash  and  tobacco  plant,  but  quickly  re- 
new^ed  when  plunged  in  w^arm  water.  In  a  moist  as  com- 
pared with  a  dry  soil,  the  quantity  would  be  greater,  but 
the  imbibing  power  the  same.  New  roots  and  scions 
springing  from  a  stump  will  cause  the  water  to  sink  in  a 
pressure  gauge.  (Hofmeister.) 

Plants  wilt  in  dry  w^eather  because  there  is  a  lack  of 
moisture  in  the  soil  to  supply  as  much  as  is  exhaled  by  the 
leaves.  More  in  fact  is  required,  as  a  portion  of  the  water 
is  fixed  in  the  plant  as  nutrition,  where  its  oxygen  and 
hydrogen  are  needed  to  supply  by  chemical  affinities  these 
important  elements. 

Although  it  has  for  a  long  time  been  believed  that  the 
exhalation  of  water  from  plants  is  indispensable  to  their 
life  and  nutrition,  as  thereby  room  is  made  for  the  upw^ird 
flow  of  nutritive  matters  held  in  solution  by  water  imbibed 
by  the  roots,  yet  there  is  strong  reason,  as  Prof.  Johnson 
says,  for  believing  that  the  current  of  water  which  ascends 
through  a  plant  is  independent  of  soluble  matters  within 
or  without  it,  and  that  soluble  matters  may  be  taken  up 
from  the  soil  even  without  an  aqueous  current.  Thus  in 
the  confined  atmosphere  of  green-houses,  where  the  air  is 
saturated  with  vapor,  and  transpiration  ceases  almost  en- 
tirely, they  seem  to  grow^  as  well  as  in  the  open  air,  where 


EXHALATION  OF  WATER. 


49 


this  process  reaches  its  maximum.  And  thus,  during  rainy- 
weather,  plants  grow  rapidly  when  there  is  but  little  if  any 
exhalation,  quite  as  much  as  in  dry  weather,  w^hen  trans- 
piration is  constantly  going  on. 

And  yet  this  process  cannot  be  considered  accidental 
or  unimportant.  Sachs  found  that  a  bean,  whose  roots 
were  in  an  atmosphere  saturated  with  aqueous  vapor, 
while  the  branches  had  fresh  air,  did  not  grow  any  while 
in  this  condition,  although  it  remained  healthy.  Knop 
also  found  that  several  kinds  of  plants  died  w^hen  confined 
in  a  vessel  over  water.  Other  causes  may  have  conspired 
to  this  end.  While  it  is  probably  true,  that  transpiration 
of  water  from  plants  is  not  essential  to  their  health  and 
growth,  its  entrance  into  them,  so  as  to  keep  up  a  due  sup- 
ply of  hydrogen,  is  a  well-established  fact. 

Some  plants  haA^e  a  much  greater  power  of  absorbing 
water  from  soils  than  others.  The  eucalyptus  tree,  from 
Australia,  is  the  most  remarkable  instance,  growing  with 
great  rapidity  in  regions  unsuitable  for  the  growth  of  forest 
vegetation.  In  marshy  lands  it  has  a  very  decided  effect 
m  draining  them  of  the  superincumbent  water,  and  in 
freeing  the  surrounding  atmosphere  from  malarial  influ- 
ences. 

31.  Exhalation  of  Water, 

Water  exhales  freely  from  growing  plants  in  the  form 
of  invisible  vapor.  The  amount  is  often  very  great.  If 
you  will  cover  a  plant  exposed  to  the  light  of  the  sun  w^ith 
a  bell  glass,  you  Avill  soon  see  the  inner  surface  of  the  glass 
covered  with  dew,  and  then  with  little  drops  which  come 
from  the  leaves. 

An  experiment  made  by  Hales  (more  than  a  century 
ago)  showed  that  a  sunflower  having  39  square  feet  of 
foliage  exhaled  3  lbs.  of  water  in  24  hours.  A  cabbage, 
whose  leaves  had  19  square  feet  of  surface,  exhaled  nearly 
as  much.    In  the  same  length  of  time  Schubler  found  that 


50 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


1  square  foot  of  pasture  grass  exhaled  5^  lbs.  of  water.  A 
recent  experiment  made  by  Knop  showed  that  a  dwarf  bean 
exhaled,  in  23  days  in  September  and  October,  13  times  its 
weight  of  Avater.  He  further  established  the  fact,  that  a 
grass  plant  will  exhale  its  own  weight  of  water  in  24  hours 
in  the  hot  dry  days  of  summer ;  and  that  a  maize  plant 
exhaled  36  times  its  own  weight  of  water  from  May  2d  to 
Sept.  4th. 

During  rainy  weather,  or  damp  days  and  dewy  nights, 
this  exhalation  almost  entirely  ceases,  while  in  dry  weather 
it  is  rapid  and  copious.  Other  things  affect  more  or  less  the 
quantity  of  water  exhaled,  as  the  age,  texture,  and  number 
of  breathing  pores  of  the  plant,  as  well  as  the  temperature 
of  the  soil.  Young  plants  also  lose  more  water  than  older 
ones,  as  ascertained  by  Lawes  and  Knop. 

Exhalation  is  not  essential  to  the  life  of  the  plant,  and 
may  be  reduced  to  its  minimum  without  affecting  its 
growth.  Only  when  the  water  exhales  faster  than  it  is 
imbibed  by  the  roots,  is  the  plant  injured;  then  it  wilts 
and  will  die,  if  the  drought  continues  too  long. 

Von  Fettenkofer  ascertained  that  transpiration  of  Avater 
in  an  oak  tree  increased  gradually  from  May  to  July,  and 
then  decreased  till  October.  The  number  of  the  leaves  on 
the  tree  were  estimated  at  751,600,  and  the  total  amount  of 
evaporation  for  the  year  at  539  cubic  centimeters  of  Avater 
for  the  Avhole  area  of  the  leaves.  The  average  rain-fall  for 
the  same  period  Avas  only  65  centimeters,  the  amount  of 
evaporation  being  8^  times  greater  than  the  rain-fall.  The 
excess  must  be  drawn  up  by  the  roots  from  a  great  depth. 
The  inference  is  very  clear,  that  trees  prevent  the  gradual 
drying  of  a  climate,  by  restoring  moisture  to  the  air  Avhich 
Avould  otherwise  be  carried  of  by  drainage. 

After  a  number  of  experiments  to  ascertain  the  pro- 
cesses of  plant  exhalation,  M.  Barthelemy  concludes  that 
aqueous  exhalations  may  result  from  plants  in  three  ways 


CIRCULATION  OF  SAP. 


51 


1.  By  insensible  exhalation  from  the  entire  surface  of 
the  cuticle  by  means  of  a  true  gaseous  dialysis. 

2.  By  sudden  emission  of  saturated  gases  which  escape 
from  the  stomata  when  the  plant  is  submitted  to  a  rapid 
elevation  of  temperature,  especially  when  enclosed. 

3.  By  accidental  exudation,  resulting  from  a  defect  in 
the  equilibrium  between  the  absorptive  action  of  the  roots 
and  the  work  of  the  parts  exposed  to  the  atmosphere,  in 
fixing  carbon  combined  with  the  elements  of  water,  work 
which  ceases  with  the  disappearance  of  light. 

We  know  that  it  is  also  right  to  conclude  that  heat 
exercises  a  strong  influence  upon  this  function,  and  that  at 
equal  temperatures  carbonic  acid  in  presence  of  light  has 
the  effect  of  diminishing  the  evaporation. 

32.    Circulation  of  Sap. 

The  roots  of  plants  are  endowed  with  a  peculiar  quality, 
by  which  they  are  enabled  to  suck  up  the  moisture  which 
comes  in  contact  with  them.  And  every  part  of  a  plant 
has  a  force  which  brings  into  play  the  suction  power  of 
the  roots.  Thus  a  root  deprived  of  its  spongioles,  a  sec- 
tion of  a  stem,  or  a  leaf,  exerts  this  suction  powder  when 
plunged  into  water. 

The  true  cause  which  produces  the  ascent  of  sap,  has 
not  been  discovered,  although  several  theories  have  been 
presented.  This  force  seems  to  be  independent  of  any 
known  law  of  hydrostatics.  We  can  conceive  how  the 
roots  might  imbibe  water  by  capillary  attraction,  but  not 
how  this  force  could  operate  with  such  rapidity  to  the 
remotest  leaves. 

Atmospheric  pressure  has  been  suggested  ;  but  from 
experiments  made  by  Hales,  it  is  evident  that  a  much 
greater  force  is  employed  than  this  can  bring  to  bear  in  a 
simple  vacuum.  He  found  that  the  pressure  exerted  by 
the  escaping  sap,  upon  the  mercury  in  a  reversed  siphon, 
caused  it  to  rise  in  one  of  the  arms,  and  remain  stationary 


52 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


at  a  height  of  thirty-eight  inches  above  its  original  level. 
The  descending  sap  is  conveyed  by  some  other  force  than 
mere  gravity,  as  has  been  proven  by  tying  a  cord  round  a 
limb  in  the  upright  and  another  in  the  depending  position. 
In  one  case  below  and  in  the  other  above  the  cord,  there 
was  a  thickening  of  the  integuments,  doubtless  from  the 
accumulation  of  the  obstructed  sap. 

Hales  supposed  that  the  motion  of  the  sap  in  plants 
depends  upon  exhalation.  Liebig  admitted  his  theory  in 
part,  but  contended  that  it  was  aided  by  some  powerful 
force  from  without,  as  atmospheric  pressure.  But  after  all 
the  experiments  that  have  been  made,  and  all  the  theories 
advanced,  we  have  to  fall  back  upon  the  old  notion  of  the 
vitcd  force^  which  we  know  exists,  and  but  little  more  in 
reference  to  it. 

Since  the  time  of  Hales,  who  experimented  a  century 
and  a  half  ago,  but  little  advance  has  been  made  in  inves- 
tigating  this  interesting  subject,  so  much  so  that  Liebig 
asserted,  that  nothing  had  been  developed  in  addition  to 
his  experiments.  We  have  now,  however,  to  record  the  re- 
sult of  an  interesting  series  of  experiments  during  the  last 
year,  1873,  conducted  by  Prof.  Peabody  of  the  Massachu- 
setts Agricultural  College,  assisted  by  Profs.  Stockbridge 
and  Goessman.  We  condense  from  President  Clark's  re- 
port the  following  summary  of  facts. 

They  prepared  six  mercurial  gauges  to  determine  the 
pressure  of  the  sap  of  different  trees.  About  sixty  spe- 
cies of  trees  and  shrubs  were  tapped,  and  it  was  found 
that  the  great  majority  do  not  bleed  from  wounds  in  the 
wood  at  any  season,  and  the  few  species  which  do  so  to 
any  considerable  extent,  only  do  it  when  deprived  of  their 
leaves.  No  reason  for  this  has  been  found  in  their  struc- 
ture or  habits. 

Of  those  which  bled,  each  species  had  their  own  time 
to  awake  from  their  winter's  repose,  the  flow  steadily 


CIRCULATIOX  OF  SAP. 


53 


increasing  in  quantity  and  force,  until  it  reached  its  max- 
imum, and  then  gradually  declined  ;  the  composition  of 
the  sap  differing  remarkably  according  to  the  date  of  the 
flow  and  the  time  of  its  beginning.  ''This  singular  peri- 
odicity," says  the  report,  peculiar  to  every  species,  de- 
monstrates that  the  absorption  of  water  by  the  rootlets  is 
not  caused  by  osmose,  or  any  other  mere  physical  force, 
but  is  the  result  of  the  specific  life  which  imparts  to  every 
plant  its  distinctive  characteristics." 

The  sugar  maple  begins  to  flow  in  October;  maximum, 
1st  of  April  ;  ceases  early  in  May.  The  black  bircli  begins 
the  last  of  March,  has  its  maximum  last  of  April,  and  ceases 
middle  of  May.  The  summer  grape  begins  first  of  May, 
reaches  its  greatest  flow  and  pressure  about  the  2oth  of  the 
same  month,  and  ends  early  in  June. 

The  principal  ingredient  of  maple  sap  was  found  to  be 
cane  sugar  ;  that  of  birch  sap,  grape  sugar,  and  of  vine 
sap,  vegetable  mucilage  or  gum.  These  three  carbo-hy- 
drates are  believed  to  be  formed  out  of  the  starch  a>  hich 
descended  and  was  deposited  in  tlie  root  the  previous 
season  ;  these  transformations  probably  occurring  in  the 
sap  after  it  begins  to  flow  in  the  spring,  thus  :  the  insolu- 
ble is  changed  into  soluble  gum,  the  gum  into  uncrystal- 
lizable  grape  sugar,  and  this  becomes  cane  sugar,  under 
favorable  circumstances. 

The  reason  why  the  maple  sap  is  changed  into  cane 
sugar,  while  the  birch  only  makes  grape  sugar,  as  inferred 
by  the  report,  is,  that  more  time  is  allowed  for  the  proper 
chemical  changes  to  take  place  in  the  one  case  than  in  the 
other.  The  maple  being  fall  of  sap  for  six  months,  between 
the  fall  of  the  leaf  and  the  beginning  of  growth  in  the 
spring,  is  the  only  tree  that  can  develop  the  grape  sugar. 
The  beginning  of  vegetable  growth  in  the  vine  is  attended 
by  the  rapid  exhaustion  of  water,  which  assimilates  the  guu- 
which  is  transformed  into  cellulose.  This  ordinarily  occurs 
with  plants  at  the  beginning  of  their  spring  growth. 


54 


ANATOMY  AN^D  PHYSIOLOGY  OF  PLANTS. 


These  experiments  further  show  that  the  weather  affects 
the  dally  and  hourly  flow,  although  the  general  flow  corre- 
sponds with  the  season,  rising  to  a  maximum  and  then 
declining,  till  it  ceases  entirely.  Steady  cold  weather,  or 
uniformly  warm,  foggy  weather,  was  the  most  unfavorable 
for  the  flow  of  sap  ;  while  freezing  nights,  succeeded  by 
sunshiny  days,  were  the  best.  Biot,  in  France,  on  the 
poplar,  and  Nevins,  in  Ireland,  on  the  elm,  found  that 
freezing  weather  forced  the  sap  from  the  alburnum  into 
the  heart  wood  of  these  trees.  Absorption  going  on  as 
usual  under  ground,  it  is  natural  to  infer  that  there  would 
be  a  rush  of  sap  to  the  surface,  and  consequently  an 
increased  flow,  as  soon  as  the  warmth  of  the  sun  expands 
the  tubes  of  the  sap  wood. 

A  piece  of  gas  pipe  being  introduced  into  the  heart 
wood,  the  flow  of  sap  was  regular  and  long  continued, 
although  not  so  abundant  as  from  the  alburnum.  This 
proves  that  the  heart  wood,  as  well  as  the  sap  wood,  is 
fllled  with  the  sap  during  the  spring.  The  flow  from  the 
heart  continued  eleven  days  longer  than  from  the  sap  of 
another  tree,  but  the  amount  from  the  sap  wood  was 
twelve  pounds  greater  than  from  the  heart. 

The  north  side  of  a  tree  yielded  twice  as  much  as  the 
south  side,  although  from  the  latter  the  flow  continued  two 
wrecks  longer. 

A  healthy  tree,  tapped  near  the  ground,  bled  six 
pounds  and  two  ounces  of  sap  in  seven  hours  ;  while  a 
limb,  Avhicli  was  cut  thirty-five  feet  above  the  ground,  did 
not  bleed  a  single  drop.  Other  experiments  showed  that 
the  sap  flowed  more  freely  twelve  feet  from  the  ground, 
while  above  that  height  it  decreased  rapidly.  This  fact 
seems  to  indicate  that  there  is  an  absorbent  power  of  the 
roots  which  forces  the  sap  upward,  as  the  force  is  weaker 
the  higher  it  ascends. 

It  is  also  inferred  from  the  fact  that  the  sap  only  rises 


CIRCULATION  OF  SAP. 


55 


about  twenty  feet  in  the  maple  tree;  that  developments 
of  leaf  and  flower  above  that  point  result  from  other 
causes  than  the  flow  of  sap  by  mechanical  force  from  below. 
Their  vitality  is  doubtless  stimulated  by  the  genial  sun- 
shine, and  their  growth  caused  by  organic  substances 
accumulated  during  the  previous  season,  and  the  absorp- 
tion of  gases  from  the  atmosphere. 

Experiments  also  proved  that  the  sap  of  the  roots  of 
maple  also  contained  sugar,  and  that  it  flowed  from  both 
ends  of  a  cut  root. 

The  largest  flow  of  sap  from  one  tree,  during  the  spring, 
occurred  'March  23d,  amounting  to  ten  pounds  and  three 
ounces  from  two  sprouts.  On  the  16th  of  December  fol- 
lowing, a  similar  tree  bled  from  two  orifices  sixteen  pounds 
and  seven  ounces.  In  November  the  sap  was  found  to 
contain  not  more  than  half  the  percentage  of  sugar  as  that 
obtained  in  March. 

It  is  not  believed  that  loss  of  the  sap  from  tapping  or 
pruning  in  the  spring  has  any  appreciable  efiect  upon  the 
growth  or  vigor  of  the  tree  or  vine.  Dr.  Jabez  Fisher 
selected  fifty  grape  vines  in  his  vineyard,  and  pruned  one 
every  day,  beginning  the  first  of  May,  until  the  young 
shoots  were  well  grown.  He  found  it  made  no  difierence 
so  the  pruning  was  done  before  the  new  growth  was  devel- 
oped. 

The  mercurial  gauge  used  in  these  experiments  w^as 
made  of  an  inverted  siphon,  the  lower  end  being  inserted 
into  the  sap  wood,  near  the  ground,  with  a  stop-cock 
attached.  The  mercury  being  poured  into  the  upper  end 
settles  down  in  the  first  bend,  until  both  tubes  are  filled  up 
to  a  certain  point.  This  is  the  zero  point,  and  the  scale 
may  be  graded  from  this.  When  the  sap  rises  and  passes 
over  the  first  bend  down  upon  the  mercury  in  the  left-hand 
tube,  it  falls  in  that,  and  rises  in  the  right-hand  tube. 
When  the  suction  toward  the  tree  takes  place,  it  rises  in 


66 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


the  left  and  falls  in  tlie  right,  and  thus  the  pressure  and 
motion  both  may  be  easily  ascertained. 

Observations  were  made  daily  from  1st  of  April  to  20th 
of  July.  The  following  facts  were  elicited  :  1st.  The  mer- 
cury generally  stood  below^  zero  in  the  morning,  and  would 
then  rise  rapidly  with  the  sun  until  the  outward  pressure 
was  sufficient  to  sustain  a  column  of  water  many  feet  in 
height."  At  seven  o'clock,  April  21st,  there  was  suction 
in  the  tree  sufficient  to  sustain  a  column  of  water  25.90 
feet.  The  mercury  began  to  rise  very  rapidly  as  soon  as 
the  sun  began  to  shine  on  the  tree,  so  that  by  fifteen  min- 
utes after  nine  a.m.  the  pressure  outward  would  have  sus- 
tained a  column  of  water  18.47  feet  high,  equal  to  a  force 
sufficient  to  sustain  44  feet  of  water.  The  next  day  the 
oscillation  was  still  more  remarkable,  representing  47.42 
feet  of  water.  No  explanation  is  given  of  the  probable 
cause  of  these  fluctuations.  2d.  The  maximum  pressure 
of  the  sap  was  equal  to  sustaining  a  column  of  water  31.73 
feet  high.  This  was  April  11th.  After  the  29th  the  mer- 
cury remained  below  zero  day  and  night.  During  the 
month  of  May  the  mercury  remained  below  zero  at  a  point 
equal  to  the  pressure  of  a  column  of  eight  feet  of  water, 
probably  caused  by  exhaustion  from  the  exhausting  leaves. 
Its  uniformity,  however,  could  not  be  accounted  for.  In 
June  it  gradually  decreased,  and  finally  the  mercury  settled 
permanently  at  zero  for  the  season. 

Two  gauges  attached  to  a  black  birch  on  the  20th  of 
April,  one  30.20  feet  above  the  other,  showed  the  next 
morning  a  difierence  of  pressure  between  them  of  29.92 
feet  of  water,  corresponding  almost  exactly  as  if  connected 
by  a  tube.  The  pressure  on  the  lower  gauge  was  56.65 
feet  of  water;  on  the  upper,  26.74.  The  upper  gauge, 
raised  twelve  feet  higher,  showed  the  same  correspond- 
ence. At  12.30  P.M.,  a  hole  bored  directly  opposite  to  the 
lower  gauge,  showed  a  diminished  pressure  in  both  gauges, 


CIECULATION  OF  SAP. 


57 


while  the  sap  flowed  freely  from  the  orifice.  In  fifteen 
minutes  one  pound  of  sap  escaped  ;  both  gauges  had  fallen 
19.27  feet  of  Avater.  On  closing  the  hole,  the  sap  rose  in 
ten  minutes  to  its  former  level. 

This  illustrates  very  clearly  that  the  whole  system  of 
sap  circulation  is  closely  and  delicately  connected,  and  also 
that  the  roots  absorb  from  the  soil,  and  carry  with  great 
rapidity,  the  nutritive  substances  requisite  for  the  support 
of  the  tree,  which  are  carried  forward  with  equal  celerity 
through  the  whole  network  of  ducts  and  tubes  to  every 
part  of  the  tree. 

By  inserting  a  stop-cock  in  the  hole  opposite  the  lower 
gauge,  it  was  found  that  the  communication  between  the 
two  gauges  was  almost  instantaneous,  showing  that  the 
tree  was  filled  with  sap,  pressing  as  freely  in  all  directions 
as  if  it  stood  in  a  cylindrical  vessel  sixty  feet  in  height. 

On  the  11th  of  May  the  sap  pressure  in  the  birch  repre- 
sented a  column  of  water  84. 7 7  feet  in  height,  the  highest 
ever  before  recorded.  The  sap  now  began  to  diminish 
and  the  buds  to  shoot  forth,  the  upper  gauge  ceasing  its 
pressure  on  the  14th,  and  the  lower  one  on  the  27th  of  May. 

In  order  to  determine  whether  any  of  the  supposed 
forces  of  exhalation,  dilatation,  contraction,  caj)illarity,  or 
oscillation,  had  anything  to  do  in  causing  the  sap  to  rise, 
a  large  root  of  a  birch,  situated  in  a  shady  ravine,  was 
followed  ten  feet  from  the  trunk,  and  carefully  cut  one 
foot  below  the  surftice,  a  piece  being  removed  between  the 
cut  and  the  tree.  To  the  end  thus  detached,  measuring 
about  one  inch  in  diameter,  was  attached  a  mercurial  gauge 
on  the  26th  of  April.  The  pressure  began  to  rise,  which 
continued  with  slight  fluctuations  till  noon  of  the  30th  ;  it 
had  attained  a  height  of  85.80  feet  of  water.  This  de- 
stroyed completely  the  idea  of  exhalation,  capillarity,  or 
any  of  the  forces,  save  the  vital  force  known  to  exist  in  the 
root. 

3* 


58 


ANATOMY  AND  PHYSIOLOGY  OF  PLANTS. 


The  experiment  of  Rev.  Stephen  Hales,  conducted  on 
the  vine  one  hundred  and  fifty  years  ago,  was  repeated, 
.  the  mercury  rising  to  49.52  feet,  six  and  a  half  feet  higher 
than  was  observed  by  him. 

The  report  concludes  very  wisely,  that  "  we  may  as 
well  admit  that  life  is  still  a  special  force,  and  not  to  be 
resolved  into  any  sort  or  combination  of  attractions  or 
repulsions,  whether  called  electricity  or  osmose,  or  any 
other  name." 

33.   Theory  of  Electrical  Force, 

As  to  one  of  the  forces  mentioned  above,  the  electrical 
by  contractility^  it  is  well  known  that  in  higher  animals 
the  muscles  and  nerves  are  possessed  of  electrical  currents, 
flowing  in  definite  directions,  which  produce  these  con- 
tractile movements.  Very  recently.  Dr.  Sanderson  has 
established  very  clearly  that  two  plants  at  least,  the  dionsea 
(Venus's  fly-trap),  and  the  mimosa  (sensitive  plant),  are 
endowed  witli  similar  currents  and  contractile  tissues, 
which  are  subject  to  the  same  laws  as  those  of  animals. 
The  dionose  grows  only  in  sandy  bogs  near  Wilmington, 
North  Carolina,  and  is  remarkable  for  its  contractile 
movements,  by  which  it  catches  insects  that  alight  upon  it, 
and,  it  has  been  supposed,  is  nourished  in  part  by  them. 

Might  it  not  be  possible  that  electrical  currents  have 
something  to  do  with  carrying  on  the  movement  oi"  fluids 
in  vegetable  as  well  as  animal  life,  since  at  least  two  species 
are  now  known  to  possess  it  ? 


PAET  11. 

AGRICULTURAL  METEOROLOGY. 


CHAPTER  I. 

THE  ATMOSPHERE.  DESCRIPTION. — RELATION  TO  VEGETA- 
TION. HEIGHT. — PRESSURE.  THE  BAROMETER.  MOIS- 
TURE.— HYGROMETER. 

34.  Description  of  the  Atmosphere. 

To  the  untaught  mind,  the  atmosphere  seems  to  be  a 
vacuum — space  without  any  substance  whatever.  A  sim- 
ple illustration  will  convince  us  of  its  substantial  quality. 
Take  a  glass  jar  with  an  open  mouth,  invert  it,  and  press 
it  down  into  water  ;  you  observe  that  the  water  does  not 
enter  it  until  turned  to  one  side  so  as  to  admit  the  escape 
of  air.  Then  it  begins  to  fill,  as  shown  by  the  bubbles 
of  air  which  escape.  For  every  volume  of  air  that  escapes, 
an  equal  volume  of  water  enters  the  jar,  until  it  is  filled. 
Upon  this  principle  the  diving-bell  is  constructed,  by 
which  a  man  may  descend  to  the  bottom  of  the  ocean, 
and  live  and  breathe  until  the  oxygen  of  the  air  is  nearly 
consumed.  This  proves  very  satisfactorily  that  the  air 
is  a  real  substance,  although  invisible. 

Then  the  atmosphere  is  composed  of  a  layer  of  light 
matter,  surrounding  the  earth  and  resting  upon  it,  which 
envelops  everything  we  see  on  or  near  its  surface.  It  is 
not  only  invisible,  but  transparent,  elastic,  destitute  of  taste 
or  smell,  and  movable  in  every  direction.    It  has  a  slight 


CO 


AGEICULTURAL  METEOKOLOGY. 


blue  tint  when  viewed  in  masses  at  a  distance.  It  has  been 
compared  to  a  vast  aerial  ocean,  surrounding  the  earth  on 
every  side  and  extending  to  a  great  height. 

The  natural  constituents  of  the  air  are  gaseous.  Liquids 
and  solids  do  sometimes  exist  in  it,  as  rain-water,  hail, 
snow,  sleet,  and  impalpable  dust  ;  but  they  are  extraneous 
to  it,  and  do  not  exist  in  a  pure  atmosphere. 

The  vajDors  which  float  in  the  air  are  properly  gases,  i 
We  become  acquainted  with  solids  and  liquids  through  the  | 
sight,  but  know  but  little  of  the  gases  by  this  method,  as 
they  are  mostly  invisible,  and  transparent  like  the  atmo-  ^ 
phere.  Gases  are  much  lighter  than  liquids  and  solids. 
Some  of  them  are  considerably  heavier  than  the  atmo- 
sphere; others  lighter.    While  most  of  them  are  colorless, 
some  possess  beautiful  colors ;  as  green,  red,  and  violet. 
Many  are  without  smell,  while  others  are  possessed  of  the 
most  pungent,  disagreeable,  and  even  poisonous  odors. 

35.  Its  Relation  to  Vegetation.  \ 

The  atmosphere  is  very  closely  related  to  vegetation, 
as  it  furnishes  much  the  largest  portion  of  the  food  of  all 
plants.  This  is  done  by  the  absorption  of  nutritive  gases 
through  the  stomata  of  their  foliage,  which  is  freely  per- 
meable to  them.  Carbonic  acid,  and  perhaps  ammonia, 
are  thus  absorbed,  and  appropriated  by  the  cells,  and  the 
structure  of  the  plant  built  up. 

The  atmosphere,  however,  has  a  natural  limit,  which 
art  cannot  improve  as  to  vegetable  nutrition.  Unlike  the 
soil,  which  may  become  exhausted  of  certain  elements,  and 
have  them  reapplied  by  art,  the  atmosphere  recuperates 
as  fast  as  the  plant  exhausts  it  of  its  appropriate  food. 
When  the  carbonic  acid  surrounding  the  foliage  is  taken 
up,  more  flows  in  by  the  law  of  diffusion,  and  an  increasing 
supply  is  thus  furnished  by  day  and  night.  The  atmo- 
sphere then,  while  of  interest,  is  only  of  secondary  import- 


HEIGHT  OF  THE  ATMOSPHERE. 


61 


ance  to  the  practical  agriculturist,  when  contrasted  with 
the  soiL 

The  common  properties  of  the  atmosphere  are  weight, 
fluidity,  and  eLasticity.  Its  pressure  depends  upon  its 
weight  and  fluidity.  Its  weight  is  owing  to  gravitation 
or  the  centripetal  force. 

Air  is  810  times  lighter  than  water,  when  the  ther- 
mometer stands  at  62°.  The  bulk  of  the  atmosphere  varies 
with  the  temperature ;  being  heavier  in  cold,  and  lighter 
in  warm  weather. 

36.  Its  Height, 

Some  philosophers  have  estimated  the  height  of  the 
atmosphere  to  be  at  least  one  hundred  miles,  inasmuch  as 
the  combustion  of  meteors  has  been  known  to  take  place 
that  far  from  the  earth.  It  is  believed  that  one-half  of 
the  whole  of  its  bulk  is  found  within  the  distance  of  3f 
miles  of  the  earth,  and  one-third  beneath  the  level  of  the 
Rocky  Mountains. 

If  the  atmosphere  had  a  uniform  density,  it  would  be 
5.208  miles  in  height  ;  but  its  density  being  proportional 
to  its  pressure,  diminishes  with  its  elevation.  It  is  sup- 
posed to  have  a  sensible  density  for  about  45  miles  in 
height,  founded  upon  the  phenomena  of  refraction. 

At  2^-^  miles  above  the  earth,  it  is  just  half  as  dense 
as  at  the  surface;  one  volume  expanding  into  two. 
At  the  same  height  above  this,  it  is  again  halved  ;  ex- 
panding into  four  volumes.  At  16^  miles  above  the 
level  of  the  sea,  it  would  be  divided  into  64  volumes; 
that  is,  it  would  be  64  times  thinner  and  lighter  than  at 
the  earth.  Although  some  suppose  that  the  atmosphere 
is  illimitable,  existing,  though  very  rare,  throughout  the 
planetary  system,  yet  it  is  probable  that  the  earth's  atmo- 
sphere has  a  true  surface  and  an  exact  limit. 


62 


AGEICULTURAL  METEOEOLOGY. 


37.  Pressure  of  the  Atmosphere, 

As  the  atmosphere  extends  many  miles  upward,  al- 
though it  becomes  thinner  and  lighter,  it  must  press  with 
considerable  weight  upon  the  earth.  This  has  been  found 
to  be  equal  to  the  pressure  of  thirty-two  feet  of  water,  if 
the  whole  earth  was  covered  at. this  depth,  or  about  thirty 
inches  of  quicksilver.  The  actual  pressure  of  the  atmo- 
sphere upon  the  earth's  surface  is  about  15  lbs.  on  every 
square  inch.  We  do  not  feel  this  pressure,  because  of  the 
mobility  of  the  air,  or  its  power  to  move  in  any  direction. 
Thus,  the  downward  pressure  is  relieved  by  pressing  upon 
every  side,  as  well  as  upward,  and  the  force  is  thus  coun- 
terbalanced. If  a  complete  vacuum  could  be  produced 
around  a  man,  he  would  be  crushed  to  the  earth  by  the 
weight  of  the  atmosphere  suddenly  pressing  down  upon  him. 

The  weight  or  pressure  of  the  atmosphere  may  be  il- 
lustrated thus  :  Take  a  hollow  globe  of  glass  and  divide 
into  two  hemispheres,  the  edges  of  which  are  made  to  fit 
very  tightly  so  as  to  exclude  the  air.  Take  a  piece  of 
paper  and  wet  in  alcohol  and  burn  within  the  globe  so  as 
to  produce  a  vacuum:  the  hemispheres  placed  together, 
having  a  handle  to  each,  cannot  be  separated  by  two 
powerful  men,  because  the  whole  pressure  of  the  atmo- 
sphere is  upon  them. 

38.   The  Barometer, 

The  barometer,  an  instrument  invented  by  Toricelli,  an 
Italian  philosopher,  indicates  the  pressure  of  the  atmo- 
sphere. It  is  made  of  a  glass  tube  about  three  feet  long, 
filled  and  then  connected  with  a  vat  of  mercury  at  its  open 
end.  Tlie  tube  thus  filled  is  inverted  with  the  finger  upon 
the  open  end,  which  is  thus  placed  in  the  vat  of  mercury. 
The  column  of  quicksilver  fails  and  leaves  a  vacuum.  The 
vat  of  mercury  is  held  in  a  leather  pouch  beneath,  so  that 
the  atmosphere  can  press  upon  it  from  below.   At  the  level 


MOISTURE  OF  THE  ATMOSPHERE. 


63 


of  the  sea  on  a  clear  day,  the  mercury  in  the  column  will 
stand  at  30  inches  above  the  bottom  of  the  vat  of  mercury. 
This  is  the  standard  for  the  barometrical  scale,  which  is  so 
graded  as  to  indicate  the  hundredth  part  of  an  inch. 

In  clear  weather  the  barometer  ranges  high,  indicating 
that  the  pressure  is  great,  and  that  there  is  but  little  mois- 
ture in  the  air,  and  no  prospect  of  rain.  If  it  falls  slowly 
and  continuously  for  several  days,  it  indicates  a  long  spell 
of  rain.  A  rapid  fall  early  in  the  morning  betokens  even- 
ing showers.    A  very  rapid  and  low  fall  forebodes  a  storm. 

The  barometer  is  well  adapted  for  measuring  the  height 
of  mountains.  For  every  87  feet  in  altitude,  it  will  fall  y^^- 
of  an  inch.  This  varies  a  little  as  between  cold  and  hot 
weather,  owing  to  the  contraction  and  expansion  of  the 
atmosphere,  as  well  as  the  mercury,  which,  however,  is 
very  slight. 

The  barometer  might  be  made  of  use  to  every  practical 
farmer  who  will  take  the  trouble  to  become  versed  in  its 
changes  and  indications.  By  it  he  wnll  be  able  to  judge, 
to  a  considerable  degree,  of  the  condition  of  the  atmo- 
sphere around  him,  and  what  it  is  likely  to  be  for  the  next 
day  or  two  ;  a  knowledge  of  which  is  very  important, 
especially  as  to  impending  rains,  as  indicating  the  kind  of 
woi'k  necessary  to  be  performed — the  sowing  of  seed,  the 
gathering  of  hay  and  fodder,  the  cutting  of  grain,  and  the 
ploughing  of  low  or  uplands. 

Every  intelligent  farmer  should  become  versed  in  what 
are  termed  the  natural  signs  of  the  weather,  especially 
those  which  foretell  rain.  The  study  of  the  barometer  (a 
science  almost  within  itself)  would  be  a  great  help  to  hira 
in  this  regard. 

39.  Moisture  of  the  Atmosphere, 

Water  exists  in  the  atmosphere  as  steam.  This,  of 
course,  is  not  liquid  water,  but  vapor  of  water,  as  the  for- 
mer is  not  volatile,  and  cannot  rise  in  the  air. 


64 


AGRICULTURAL  METEOROLOGY. 


A  body  whose  temperature  is  far  lower  than  the  at- 
mosphere, will  condense  vapor  from  the  air.  Thus  a  tum- 
bler of  ice-water  on  a  warm  day  gathers  dew  on  the  out- 
side. And  from  the  same  cause,  on  calm  summer  nights, 
the  ground,  grass,  and  other  bodies  where  the  temperature 
suddenly  falls  from  the  abstraction  of  the  sun's  rays,  is 
covered  with  dew.  In  the  same  way,  invisible  vapor  issu- 
ing from  a  steam  boiler  into  the  cold  air,  forms  a  cloud, 
which  is  composed  of  minute  drops  of  water.  And  thus, 
by  the  rapid  evolution  of  the  air  from  any  cause,  fogs  and 
clouds  are  produced.  When  the  change  is  very  rapid,  the 
minute  droplets  aggregate  into  full  drops  of  water  in  the 
form  of  rain,  and  fall  to  the  ground  in  showers. 

The  properties  of  the  atmosphere  are  modified  to  a 
considerable  extent  by  the  quantity  of  vapor  in  it,  which 
is  always  limited  by  temperature,  and  is  deposited  sooner 
or  later  as  dew  or  rain  ;  returning  to  the  seas,  rivers,  and 
soil,  from  whence  it  came. 

We  must  not  confound  the  dampness  or  relative  hu- 
midity of  t 'le  atmosphere  with  its  absolute  humidity.  The 
relative  humidity  indicates  the  proximity  of  the  atmosphere 
to  saturation  or  condensation  ;  a  state  dependent  on  the 
mutual  influence  of  absolute  humidity  and  temperature. 
From  numerous  experiments  of  Kaemtz  on  the  shores  of  the 
Baltic,  the  relative  humidity  is  highest  in  the  morning  be- 
fore sunrise,  and  lowest  at  the  hour  of  the  greatest  diur- 
nal heat.  This  corresponds  with  results  obtained  in  this 
country. 

40.  Evaporation, 

If,  on  a  dry  day,  you  pour  water  in  an  open  shallow 
vessel,  you  will  soon  perceive  that  it  gradually  disappears. 
It  has  risen  in  the  form  of  vapor,  and  mingles  with  the 
atmosphere.  This  process  is  called  evaporation.  Even 
snow  and  ice  of  a  cold  day  will  thus  suffer  loss. 

There  are  three  circumstances  which  govern  the  spon- 


iiygkomi:teh. 


65 


taneous  evaporation  of  water,  viz.  the  dryness  oi  the  air, 
its  warmth,  and  its  mobility  by  currents.  Water  emits 
double  the  quantity  of  vapor  at  60°  that  it  does  at  40°. 
Hence  humid,  hot  air  contains  much  more  moisture  than 
when  it  is  cold  ;  and  this,  moved  by  rapid  currents  of  air 
as  on  a  windy  day,  will  cause  a  much  more  rapid  escape 
of  vapor  than  in  calm  weather. 

Evaporation,  then,  is  constantly  going  on  from  oceans, 
seas,  and  lakes,  as  w^ell  as  the  land,  wherever  there  is  mois- 
ture in  the  earth.  This  passes  upward  in  vapor,  gathers  in 
clouds,  and  falls  again  to  the  earth  in  rain.  Water  may 
also  exist  as  a  liquid  in  the  atmosphere,  but  it  is  only  when 
rain  is  formed  from  vapor. 

The  amount  of  vapor  in  the  atmosphere  is  very  variable, 
ranging  from  a  half  to  three  and  a  half  per  cent.,  and  aver- 
aging about  three  per  cent  When  the  air  is  very  damp 
it  becomes  saturated,  and  is  deposited  on  window  glass  and 
other  cool  surfaces.  When  dry,  it  is  always  capable  of 
taking  up  more  moisture;  hence,  evaporation  goes  on  at  a 
rapid  rate. 

41.  Hygrometer. 

The  hygrometer  is  another  useful  instrument  to  the 
agriculturist.  It  indicates  the  amount  of  humidity  in  the 
atmosphere ;  and  of  course  where  there  is  most  moisture 
there  is  a  greater  prospect  of  rain,  all  other  things  being 
equal.  This  instrument  has  been  variously  constructed, 
both  in  form  and  principle. 

The  hygrometer  of  Prof.  Daniel  (considered  the  best, 
because  it  involves  the  principle  of  condensation)  is  con- 
structed as  follows  :  A  glass  tube  is  bent  twice  at  right 
angles  and  suspended  on  a  pillar,  having  a  bulb  at  each  end. 
One  of  these  bulbs  is  partially  filled  with  ether,  into  w^hich  a 
delicate  thermometer  dips,  being  inserted  within  the  tube, 
from  which  the  air  is  entirely  expelled,  and  it  contains 
nothing  but  the  ethereal  vapor.  The  other  bulb  is  covered 
with  a  thin  piece  of  muslin.    The  pillar  hns  a  thtrmometer 


GG 


AGEICULTURAL  MFTEOKOLOGY. 


attached  to  it,  which  indicates  the  temperature  of  the  exter- 
nal air. 

The  amount  of  m.oisture  in  the  atmosphere  at  a  given 
time,  is  obtained  by  placing  the  instrument  in  an  open 
window,  or  in  some  place  to  communicate  with  the  exter- 
nal air,  and  a  few  drops  of  pure  ether  poured  on  the  muslin 
covering  one  of  the  bulbs.  The  ether  evaporating  rapidly, 
causes  a  fall  of  temperature  in  the  tube,  condenses  the  ethe- 
real vapor  within,  and  evaporates  the  ether  in  the  other 
bulb.  A  consequent  reduction  of  temperature  takes  place 
in  the  enclosed  thermometer.  Soon  the  atmospheric  vapor 
will  be  seen  gathering  in  a  ring  upon  the  glass.  At  the 
moment  this  transpires,  Avhich  is  called  the  dew  point,  note 
the  difference  between  the  two  thermometers.  If  the  ex- 
ternal stands  at  65^,  and  the  internal  at  60^,  the  dryness  of 
the  atmosphere  is  indicated  by  5^.  If  the  external  ther- 
mometer is  75°,  and  the  internal  60°,  the  indication  of  dry- 
ness is  15^,  showing  less  humidity  by  10°. 

In  England,  which  is  a  damp  climate,  the  dew  point 
seldom  reaches  30°  F.  ;  while  in  the  hot,  dry  clime  of  Italy, 
a  difference  has  been  noticed  of  61°,  the  internal  thermome- 
ter running  down  from  90°  to  29°. 


CHAPTER  II. 

TBMPERATURE  OF  THE  ATMOSPHERE. — THE  THERMOMETER. 
FOGS. — DEW. — FROST.  SNOW.  HAIL. 

42.  Temperature, 

The  temperature  of  the  atmosphere  regulates  that  ol 
the  soil ;  and  it  has  been  found  that  different  seeds  will 
geraiinate  in  any  climate,  when  the  sum  of  all  the  means 
of  the  thermometer  reaches  a  certain  point — some  requir- 
ino-  more  heat  than  others.    1  doubt  not  this  would  be 


TEMPEKATURE. 


61 


exactly  true  in  the  same  class  of  soils.  But  as  soils  are  so 
variable  as  to  warmth,  moisture,  etc.,  an  approximation  is 
all  that  could  be  expected.  True  isothermal  lines  might 
thus  be  established,  as  to  the  cultivation  of  different  plants, 
as  well  as  the  best  time  for  the  deposition  of  seeds  in  the 
soil. 

The  lower  strata  of  air  near  the  earth  is  warmed  in 
two  ways  :  by  the  luminous  beams  of  the  sun,  and  by  the 
radiation  of  heat  from  the  earth  itself.  Kaemtz  and  Martin 
state  that  the  atmosphere  absorbs  nearly  half  of  the  daily 
amount  of  the  heat  emitted  by  the  sun,  even  when  the  sky 
is  perfectly  serene.  The  remaining  portion  strikes  the 
earth,  and  elevates  its  temperature,  which  sends  back  in- 
visible rays  of  heat  to  the  lower  strata  of  the  atmosphere 
by  radiation.  Modern  researches  show  that  all  bodies  ab- 
sorb more  of  the  non-luminons  rays  of  heat. 

The  radiation  of  heat  from  the  earth  is  effected  by  cli- 
mate and  local  causes.  Though  there  is  much  more  heat 
during  the  whole  year  at  New  Orleans  than  at  Montreal,  for 
instance,  there  is  more  received  durins;  the  three  summer 
months  at  the  latter  than  at  the  former  place,  owing  to  the 
greater  amount  of  radiated  heat.  The  atmosphere  trans- 
mits the  penetrating  rays  of  tlie  sun  to  the  earth,  which 
absorbs  them,  and  radiates  other  rays  of  heat  not  so  pen- 
etrating, which  are  retained  in  the  atmosphere  near  the 
earth,  and  add  to  its  warmth.  Thus  w^e  see,  that  in  com- 
paring the  agricultural  capacity  of  different  latitudes,  we 
must  remember  to  allow  for  the  radiation  of  heat  from  the 
earth,  as  well  as  the  direct  rays  of  the  sun. 

There  is  much  greater  radiation  of  heat  shown  in  dry 
places  like  African  deserts,  where  the  days  are  very  hot  and 
the  nights  cold,  than  under  other  circumstances.  Colonel 
Emory  observed  a  difference  of  60^  between  day  and  night 
on  some  of  the  Western  plains. 

From  actual  experiments  made  it  has  been  ascertained 


68 


AGRICULTUKAL  METEOROLOGY". 


that  air  expands  1.491  parts  of  its  bulk  above  the  freezmg 
point,  for  every  degree  of  heat.  Heated  air  is  therefore 
specifically  lighter,  and  its  tendency  is  constantly  to  ascend. 

Every  pound  of  air,  according  to  Dalton,  contains  an 
equal  amount  of  heat;  and  as  it  is  more  expanded  in  the 
higher  regions,  it  is  of  course  cooler.  The  amount  of  vapor 
in  the  atmosphere,  as  well  as  its  density,  modifies  the  heat. 

It  has  been  ascertained  that  for  every  352  feet  of  ascent, 
the  temperature  rises  one  degree.  This  is  owing  to  two 
principal  causes:  1st,  the  fact  that  air  becomes  colder  by 
expansion;  2d,  that  the  atmosphere  derives  its  heat  mostly 
from  the  earth. 

The  surface  of  the  earth  is  much  more  heated  by  the 
sun  than  that  of  the  ocean  ;  inasmuch  as  the  rays  of  heat 
enter  the  ground  but  little  more  than  half  an  inch  during 
a  long  summer  day;  while  in  the  same  length  of  time  they 
jDenetrate  the  ocean  many  fathoms  deep.  Thus  the  surface 
of  the  earth  is  heated  many  times  more  than  that  of  the 
sea.  This  has  much  to  do  with  the  aerial  currents.  For 
as  the  heated  strata  above  the  continents  are  continually 
rising,  the  cooler  atmosphere  of  the  ocean  moves  to  fill  up 
the  partial  vacuum  thus  produced.  This  is  the  cause  of  the 
sea  breeze,  which  is  ever  blowing  from  the  land  to  the  sea,  or 
vice  versa, 

43.   The  Thermometer. 

The  thermometer^  as  you  all  know,  is  the  instrument 
which  indicates  the  temperature  of  the  atmosphere.  The 
one  commonly  used  in  this  country  and  England  is  Fah- 
renheit's, the  scale  of  which  begins  at  zero,  32^  below  the 
freezing  point.  The  centigrade  thermometer,  used  prin- 
cipally in  France,  has  it  zero  at  the  freezing  point,  and 
numbers  100  degrees  between  that  and  boiling.  The  same 
points  are  divided  into  180^  in  Fahrenheit's,  so  that  one 
degree  centigrade  is  equal  to  If  Fahrenheit. 

This  instrument  consists  of  a  small  glass  tube,  termi- 


FOGS. 


69 


nated  by  a  bulb,  which  is  filled  with  mercury,  having  enough 
in  the  tube  to  stand  at  a  mark  indicating  32^  when  sur- 
rounded by  ice.  The  tube  itself,  having  previously  been 
made  a  vacuum  by  heat,  and  the  pressure  of  the  mercury, 
is  inverted  and  hermetically  sealed.  For  frigid  climates, 
the  thermometer  is  graded  to  40^  below  zero,  the  point 
at  which  mercury  freezes.  Below  that  point,  a  spirit  ther- 
mometer has  to  be  used. 

Tlie  thermometer  is  an  important  instrument  to  agri- 
culturists, and  even  practical  farmers.  The  daily  mean 
temperature,  kept  for  years,  would  be  of  great  value  in  a 
given  locality.  This  can  be  approximated  by  noting  the 
temperature  during  the  morning  twilight,  at  2  p.m.,  and 
one  hour  after  sunset  each  day.  The  three  added  together 
and  averaged,  would  about  equal  the  sum  of  all  the  hours, 
day  and  night,  taken  separately  and  divided  by  24. 

For  scientific  observations,  a  simple  exposure  to  the 
external  air  for  the  morning  and  evening  hours  will  suffice, 
but  at  2  r.M.,  Avhen  the  sun  is  shining,  more  care  must  be 
taken  in  locating  the  instrument.  A  place  exposed  to  the 
general  warmth  of  an  external  atmosphere  must  be  selected, 
without  the  slightest  reflection  from  ground  or  wall.  A 
bay  window  with  blinds,  on  the  shady  side  of  the  house,  or 
a  similar  structure  under  an  umbrageous  tree,  would  sub- 
serve the  end. 

44.  Fogs, 

According  to  Scripture,  there  was  no  rain  before  the 
flood;  "but  there  went  up  a  mist  from  the  earth  and 
watered  the  whole  face  of  the  ground."  This  mist  seems 
to  have  been  produced  very  much  like  our  dews,  though 
much  heavier,  as  it  sufficed  for  vegetation.  The  difference, 
however,  between  our  mist  and  dews,  is  that  the  one  is 
visible,  the  other  invisible. 

Fogs  or  mists  are  visible  vapors  floating  near  the  sur- 
face of  the  earth,  and  are  always  the  result  of  a  slight 


10 


AGIUCULTURAL  METEOKOLOGY. 


precipitation  of  moisture.  The  only  difference  between 
mist  and  rain  is  that  the  one  falls  from  a  thin  cloud  near  the 
surface  of  the  earth,  being  composed  of  the  smallest  drop- 
lets of  water;  while  the  other  falls  from  a  dense  cloud  at  a 
distance  from  the  earth  formed  by  a  copious  precipitation 
of  moisture ;  the  cloud  itself  being  a  thick  mist  of  drop- 
lets, which  mingling  in  their  fall  become  smaller  or  larger 
drops  of  rain,  according  to  circumstances,  before  they 
reach  the  earth. 

Saussure  and  Kratzenstein  found  that  mists  were  com- 
posed of  minute  globules  of  water,  which  they  supposed  to 
be  hollow,  as  they  possessed  rings  of  prismatic  colors  like 
soap  bubbles,  which  could  only  exist  in  globules  of  w^ater 
without  air. 

Fogs  are  not  common  in  hot  climates,  or  during  the 
hottest  part  of  the  day  in  temperate  latitudes.  They  fre- 
quently occur,  however,  in  the  latter,  but  to  a  small  extent 
compared  with  the  polar  regions.  There,  at  the  approach 
of  w^inter,  the  whole  surface  of  the  ocean  steams  with  va- 
por, csillecl  frost  sinoJce,  It  disappears,  however,  when  the 
cold  weather  sets  in. 

These  i3olar  fogs  are  caused  by  the  warm  air  of  the 
ground  during  summer,  mingling  with  cold  air  of  the  ice- 
bound shores.  According  to  Simpson,  the  thermometer 
sometimes  rises  to  71^  on  the  land,  while  the  shores  are 
lined  with  ice  of  immense  thickness.  These  dense  fogs 
cause  it  to  be  so  dangerous  to  navigate  the  polar  seas. 

The  fogs  which  rise  from  rivers  are  produced  by  the 
much  more  rapid  radiation  of  heat,  during  the  day,  from  the 
banks  than  from  the  running  stream.  As  soon  as  the  tem- 
perature is  equalized  by  the  morning  sun,  they  disappear. 

Mountains  and  high  hills  are  more  subject  to  fogs  than 
level  plains,  from  the  mingling  of  the  warm  air  of  the 
vales  with  their  summits.  Dense  forests  produce  fogs,  and 
even  light  showers  of  rain,  when  the  cool  air  of  their  shady 


DEW. 


recesses  rises  and  mingles  with  the  heated  air  of  their  sunny- 
tops. 

Mists  are  always  beneficial  to  growing  crops  in  our 
hot  summer  weather,  to  the  extent  that  they  deposit 
moisture  on  the  surface  of  the  earth,  as  it  increases  the 
hygroscopic  water  of  the  soil,  especially  in  clay  soils  and 
vegetable  moulds.  Indeed,  we  cannot  appreciate  the  value 
of  even  the  invisible  vapors,  which  float  near  the  earth 
during  long  summer  droughts,  as  the  thirsty  soil  absorbs 
enough  moisture  from  them  to  sustain  life  in  the  plant 
till  the  rain  comes.  This  is  one  reason  why  soils  abound- 
ing in  clay  and  organic  matter  prolong  the  health  and 
life  of  plants  for  days  after  they  have  succumbed  in  hot 
sandy  lands. 

45.  Dew, 

DeiL\  another  important  source  of  moisture  to  plants 
in  certain  seasons,  is  spontaneously  deposited  during  clear, 
calm  nights,  on  the  surfaces  of  all  bodies  exposed  to  the 
atmosphere.  During  the  day,  the  earth  as  well  as  the 
lower  strata  of  air,  becomes  heated  by  the  direct  rays  of 
the  sun  ;  as  night  approaches,  it  loses  its  heat  very  rapidly 
by  radiation,  and  falls  as  fast  in  temperature.  But  the 
earth  loses  its  heat  more  rapidly  than  the  air,  there 
being  sometimes  as  much  as  15*^  difference.  Thus  the 
stratum  of  air  immediately  in  contact  Avith  the  earth  is 
cooled  down  rapidly,  its  vapor  condensed,  and  deposited  as 
dew  upon  the  earth,  and  substances^lying  upon  its  surface. 

A  body,  then,  must  be  colder  than  the  contiguous  at- 
mosphere before  the  dew  can  be  deposited  upon  it,  and 
the  greater  the  difference  in  temperature,  other  things 
being  equal,  the  greater  the  amount  of  dew. 

Dew  can  be  formed  only  when  the  atmosphere  is  calm 
and  clear;  hence  it  is  not  deposited  on  cloudy  or  windy 
nights.  The  clouds  reflect  back  the  radiated  heat  of  the 
earth,  and  keep  the  intermediate  atmosphere  of  an  equable 


12 


AGRICULTURAL  METEOIICLGGY. 


temperature,  so  that  it  cannot  be  formed.  Dr.  Wells  demon- 
strated this,  as  follows  :  On  a  clear  night,  a  thermometer 
laid  upon  the  grass  stood  at  32^.  The  sky  being  suddenly 
overcast  with  clouds,  it  rose  in  twenty  minutes  to  39^  ; 
and  in  the  same  length  of  time  sank  down  to  32*^  again 
when  the  sky  became  serene. 

When  there  is  wind  no  dew  is  formed,  because  a  vol- 
ume of  air  cannot  remain  long  enough  in  contact  with 
the  cold  surface  of  the  earth  for  its  moisture  to  be  con- 
densed. A  slight  agitation,  however,  will  prove  favorable 
rather  than  otherwise  to  the  deposition  of  dew. 

As  the  substance  bedewed  must  be  colder  than  the  sur- 
rounding atmosphere,  it  is  easily  perceived  how  bodies 
which  rapidly  lose  their  heat,  and  slowly  acquire  it  from 
others,  are  more  affected  than  others.  Thus  glass,  and 
bodies  of  a  porous  texture,  such  as  wool  and  silk,  are  copi- 
ously bedewed,  while  metals  and  rocks  are  not,  because  the 
warm  soil  below  easily  and  rapidly  restores  their  lost  heat. 

Dew  is  sometimes  formed  just  before  sunset,  in  conse- 
quence of  the  earth  losing  more  heat  than  it  receives  from 
the  rays  of  the  declining  sun.  And  so  in  shady  places  after 
sunrise,  the  same  effect  may  be  produced  where  the  low 
temperature  of  the  earth,  which  has  been  gradually  cooling 
during  the  night,  is  not  immediately  influenced  by  the 
w^armth  of  the  rising  sun. 

Most  dew  will  always  be  formed  when  there  is  most 
humidity  in  tlie  air.  The  heavy  dews  of  September,  the 
driest  month  of  the  year,  supply  to  a  large  extent  the 
needful  moisture  to  the  cotton  plant,  and  keep  it  in  a 
thrivins:  condition  with  but  little  rain. 

46.  Frost. 

Hoar  frost  is  frozen  dew,  and  of  course  results  from  tlie 
same  causes,  only  it  requires  the  temperature  of  the  earth 
to  be  below  tlie  freezing  point,  while  the  atmosphere  a 


IS 


few  feet  from  it  is  several  degrees  liiglier.  The  formation 
of  frost  is  arrested  by  anything  which  prevents  the  radia- 
tion of  heat.  Hence  plants  situated  under  trees  are  not  so 
liable  to  be  frozen. 

Ploughed  land  is  much  more  subject  to  frost  than  that 
which  has  not  been  recently  disturbed,  as  the  radiation 
of  heat  is  much  more  rapid,  owing  to  the  many  angular 
points  of  surface  it  presents.  We  once  ploughed  a  few 
rows  of  corn  on  a  cold  evening  of  spring  :  the  next  morning 
it  was  cut  down  by  the  frost,  while  the  adjoining  rows  were 
unhurt.  ♦ 

Frost,  as  before  stated,  is  very  beneficial  to  land  in 
pulverizing  the  soil  by  the  force  of  expansion,  uj)on  a 
principle  in  nature  which  seems  to  have  been  specially 
instituted  for  a  benevolent  purpose  ;  wdiile  cold  contracts 
everything  else,  it  causes  water  to  expand  when  con- 
gealed. But  for  this,  ice  would  sink  to  the  bottom  of 
rivers  and  oceans,  and  accumulate  in  such  masses  as  to 
freeze  the  earth  into  an  icicle. 

Sometimes,  frost  is  very  disastrous  to  gardens,  orchards, 
and  crops.  We  may  protect  tender  plants  in  a  small  way 
by  covering  them  so  as  to  prevent  radiation.  Vine-yards 
have  been  saved  by  building  fires,  and  enveloj^ing  them  in 
smoke  during  the  night.  Late  planting  is  the  best  pro- 
tection against  frost  ;  and  a  judicious  farmer  can  gene- 
rally tell  from  the  budding  of  forest  trees,  when  the 
ground  is  warm  enough  for  seeds  to  germinate  rapidly,  and 
plants  to  grow  healthily.  Once  in  a  lifetime,  under  such 
circumstances,  the  frost  might  kill  them,  but  it  would  be 
very  rare  indeed. 

,    47..  Snoio, 

Snow  is  frozen  moisture  that  descends  from  the  atmo- 
sphere in  the  form  of  white  crystals  or  flakes,  when  the 
4 


?4 


AGRICULTURAL  METEOROLOGY. 


temperature  of  the  air  at  the  earth's  surface  is  near  the 
freezing  point.  When  the  air  abounds  in  vapor,  large 
flakes  form  ;  the  reverse  causes  fine  snow.  The  crystals 
of  snow  contain  air,  which  prevents  the  transmission  of 
of  light;  otherwise  they  would  be  transparent  like  other 
pure  crystals. 

The  needle-like  crystals  of  snow  often  differ  very  much 
in  the  arrangement  of  their  spiculse  ;  but  those  of  the  same 
storm  are  said  to  be  always  alike. 

The  bulk  of  snow  is  ten  or  twelve  times  greater  than 
the  water  of  which  it  is  composed. 

Red  and  i^reen  snow  have  been  observed  in  northern 
latitudes,  existing  in  some  instances  in  large  quantities. 
They  are  produced  by  microscopic  plants,  which  are 
capable  of  existing  at  very  low  temperatures,  and  are 
said  to  flourish  with  remarkable  vigor.  They  are  formed 
of  globules  which  vary  in  diameter  from  one  thousandth 
to  three  thousandths  of  an  inch.  The  cells  are  red,  which 
is  believed  to  be  their  natural  color,  the  green  tint  result- 
ing from  exposure  to  air  and  light. 

Snow  is  useful,  agriculturally,  in  preserving  the  internal 
warmth  of  the  earth  by  preventing  the  radiation  of  heat, 
and  in  this  way  acts  beneficially  on  grain  crops.  Oftentimes 
in  a  temperate  climate,  wheat  is  winter-killed;  when  it  is 
protected  in  higher  latitudes  by  a  covering  of  snow. 

Ammonia  also  is  held  in  the  soil  and  appropriated  to 
the  benefit  of  the  plants,  which  would  otherwise  be  volatil- 
ized by  sunshine  and  winds.  Even  the  temjDcrature  of  the 
tropics  is  modified  and  improved  by  the  wind  from  the 
snow-capped  mountains,  which  are  the  natural  refrigera- 
tors of  southern  climes ;  and  thus  far  plants  as  well  as 
animals  are  benefited,  and  enabled  to  better  Avithstand  the 
burning  heat  of  a  vertical  sun. 


HAIL. 


75 


48.  Hail. 

Hall  is  water  frozen  in  the  upper  regions  of  the  atmo- 
sphere, whicli  usually  falls  in  summer  during  the  hottest 
part  of  the  day.  It  is  very  destructive  at  times  to  grow- 
ing crops,  but  is  generally  confined  to  very  narrow  limits. 
Its  origin  has  been  a  vexed  question  with  meteorologists. 
Volta  attributed  it  to  the  cold  produced  by  electricity. 
Hence  in  France,  where  hail-storms  are  very  disastrous  to 
crops,  they  erected  hail-rods  to  draw  off  the  electricity^ 
This  theory,  however,  proved  to  be  fanciful,  and  the  rods 
ineffectual. 

Olmstead's  theory  of  warm  currents  from  the  tropics 
and  cold  ones  from  the  polar  regions  being  suddenly 
brought  together  by  the  force  of  storms  and  whirlwinds, 
causins;  sudden  condensation  and  freezino;  of  the  atmo- 
spheric  vapors,  is  certainly  more  logical  ;  particularly  as 
the  temperate  regions,  where  such  currents  meet,  are  al- 
most exclusively  visited  by  hail-storras. 

Hail,  though  produced  by  cold,  occurs  only  in  summer 
in  warm  climates  and  seldom  at  night.  An  ascending  cur- 
rent of  humid  air  could,  by  rarefraction  (having  an  upward 
velocity),  be  capable  of  sustaining  the  falling  hail-stones 
until  they  are  sometimes  very  large.  Hail-storms  are 
always  attended  with  thunder  or  electrical  discharges; 
hence  the  origin  of  the  idea  that  thunder-rods  might 
protect  from  their  devastations.  (Graham.) 

The  formation  of  hail  is  a  blessing  even  to  the  farmer ; 
for  in  its  freezing  into  solid  ice,  the  rain  is  prevented  from 
falling  in  chilling  torrents,  which  passing  through  currents 
near  the  freezing  point  would  seriously  injure  the  crops. 
Besides,  the  latent  heat  of  the  rain  becomes  sensible  heat, 
which  being  cariied  off  by  the  cold  current,  causes  its 
temperature  to  rise,  and  thus  it  falls  in  warm,  genial 
showers,  even  during  a  hail-storm. 


10 


AGRICULTUP.AL  METEOROLOGY. 


CPIAPTER  III. 

CLOUDS  AND  RAIX. 

49.  Formation  of  Clouds, 

Clouds  are  collections  of  vapor,  which  float  above  the 
earth,  most  generally  at  a  lofty  height.  Tlie  only  differ- 
ence between  them  and  fogs  is  in  their  elevation. 

When  warm  and  cold  air  unite  in  the  upper  regions, 
the  combining  volumes  having  a  slight  excess  of  humidity, 
clouds  are  formed.  As  evaporation  takes  place  from  the 
earth,  warm  currents  of  humid  air  are  continually  ascend- 
ing, and  as  they  meet  the  colder  atmosphere  above,  clouds 
form.  The  higher  they  ascend,  and  the  colder  the  at- 
mosphere above,  the  larger  and  more  numerous  will  the 
clouds  be.  They  redissolve,  however,  into  invisible  vapor 
when  they  meet  with  warm  currents  of  air,  as  they  ascend 
or  descend  nearer  the  earth,  where  the  temperature  is 
always  warmer  during  sunshiny  weather. 

It  is  only  when  the  excess  of  moisture  is  small  that 
clouds  are  formed,  from  the  ever-changing  currents  of 
warm  and  cold  air  which  float  at  various  heights  and  in 
different  directions  many  thousand  feet  above  the  earth. 

Of  clear  summer  mornings  there  are  no  clouds  ;  but  to- 
ward noon,  as  the  heated  air  near  the  earth  begins  to  rise 
and  mingle  with  the  cooler  air  above,  saturation  takes  place, 
and  clouds  form.  If  there  is  humidity  enough,  rain  will 
fall  after  the  heat  of  the  day.  Hence  nearly  all  our 
summer  rains  are  in  the  afternoon. 

50.  Height  of  Clouds. 

Clouds  vary  much  in  altitude.  Peytier  and  Hossard, 
two  French  engineers  stationed  on  the  Pyrenees,  estimated 
the  lower  surface  of  forty-eight  different  clouds  to  range  in 


OFwIGIXAL  CLOUDS. 


I^ight  from  1,476  to  8,200  feet.  Daltoii  states  that  two- 
fifths  of  all  the  clouds  observed  in  England  for  five  years 
averaged  more  than  3.150  feet  above  the  surface  of  the 
earth.  Gay-Lussac  in  1804  ascended  in  a  balloon  23,000 
feet,  and  beheld  clouds  floating  above  him  at  a  much 
greater  height. 

According  to  Kaenitz,  who  had  collected  many  obser- 
vations on  the  subject,  clouds  range  in  height  from  1,300 
to  23,000  feet.  It  is  certain,  however,  that  they  float 
higher  than  this  estimate,  as  Chimborazo  is  21,840  feet 
above  the  sea,  and  they  have  been  seen  floating  above  the 
summit  of  this  mountain. 

Clouds  were  observed  by  Peytier  and  Hossard  to  be  as 
mucli  as  2,788  feet  thick,  or  more  than  half  a  mile.  Others 
were  only  1,476  feet,  on  another  day. 

51.    Original  Clouds, 

Meteorologists  divide  clouds  into  seven  diflerent  kinds. 
Three  original,  viz.  .cirrus,  cumulus,  and  stratus ;  and 
four  combined,  viz.  cirro-cumulus,  cirro-stratus,  cumulo- 
stratus,  and  nimbus. 

Cirrus  clouds  are  so  named  from  the  Latin  word  sig- 
nifying a  curl^  because  it  frequently  assumes  the  form  of 
a  lock  of  hair.  It  is  of  a  light  fleecy  appearance  and  light 
structure,  and  is  capable  of  assuming  a  variety  of  forms. 

After  a  fine  spell  of  weather  cirrus  are  generally  the  first 
precursors  of  a  change.  They  stretch  across  the  sky  as 
white  slender  filaments,  thready,  and  arranged  in  parallel 
bands,  sometimes  spreading  out  like  the  tail  of  a  horse, 
called  by  the  sailors  wind  trees  or  mares'  tails^  which  to 
them  denote  stormy  weather. 

The  cirrus  soars  above  all  the  other  clouds.  Kaemtz,  at 
Halle,  Germany,  estimated  them  to  be  frequently  21,300 
feet  above  the  earth.  He  came  to  the  conclusion  that 
they  were  entirely  composed  of  snowflakes.    This  is  no 


IS 


AGRICULTURAL  METEOROLOGY. 


doubt  true  in  some  cases,  as  the  elevated  regions  they 
occupy  must  often  be  far  below  the  freezing  point. 

Cumulus,  the  Latin  word  for  a  heap,  has  been  applied 
to  that  class  of  clouds  which  are  piled  up  one  upon  an- 
other. They  are  usually  in  the  form  of  a  hemisphere, 
resting  upon  a  horizontal  base.  This  is  properly  the  day 
cloud,  as  it  is  rarely  seen  at  night,  unless  after  the  evening 
twilight,  and  seldom  early  in  the  morning  or  during  the 
winter. 

These  clouds  are  produced  by  the  ascending  cuiTents 
of  warm  air  caused  by  solar  heat.  In  the  clear  open 
weather  of  summer,  about  noontide  or  before,  small  specks 
of  these  clouds  may  be  seen,  generally  in  the  northwest, 
rising  toward  the  zenith.  As  they  approach  they  become 
thicker  and  larger,  during  the  heated  portion  of  the  day, 
but  disappear  toward  nightfall.  This  is  frequently  re- 
peated for  several  days,  the  clouds  becoming  larger  and 
more  numerous  until  rain  comes,  or  they  are  dissipated  by 
the  winds. 

Cumulus  clouds  float  lower  of  a  morningf,  increasino;  in 
altitude  with  the  ascending  currents  of  heat,  and  then  de- 
scend again  as  the  heat  of  the  day  declines.  Meteorolo- 
gists stationed  on  high  mountains,  have  observed  these 
clouds  below  them  in  the  morning,  around  and  above 
them  during  the  heat  of  the  day,  and  then  descending 
again  to  the  vale  below  in  the  cool  of  the  evening. 

Saussure  attributed  their  rounded  figure  to  their  mode 
of  formation.  When  one  fluid  flows  through  another  at 
rest,  the  outline  of  the  figure  formed  always  represents  a 
curve.  This  is  illustrated  by  a  drop  of  milk  or  ink  falling 
into  a  glass  of  water,  or  a  cloud  of  steam  issuing  from  a 
steam  boiler. 

The  stratus  is  properly  a  night  cloud,  from  the  Latin, 
a  covering.  It  generally  forms  about  sunset,  increases  in 
density  during  the  night,  and  disappears  early  in  the  morn- 
ing.   It  is  caused  by  the  vapors  which  have  been  exhaled 


COMBINED  CLOUDS. 


79 


during  the  clay,  settling  toward  night  nearer  the  earth, 
around  the  horizon.  To  the  same  class  belong  those  light 
elongated  clouds,  Avhich  gather  over  the  meadows  and 
vales  toward  a  summer's  eve:  this  jDhenomenon  is  regarded 
by  the  common  people  as  the  settling  of  smoke,  and  is  a 
popular  sign  of  approaching  rain. 

52.    Combined  Clouds. 

The  eiri'O' stratus  cloud  is  a  combination  of  the  cirrus 
and  stratus.  It  is  generally  remarkable  for  its  length  in 
proportion  to  its  thickness;  but  assumes  a  variety  of  forms 
— sometimes  appearing  in  a  streak,  broad  at  the  middle  and 
narrow  at  both  ends,  and  then  like  a  number  of  parallel 
bars,  and  again  in  sriiall  rows  of  diminutive  clouds  parallel 
to  each  other.  In  another  form  it  overspreads  the  whole 
sky  Avith  a  thin,  gauze-like  appearance,  through  which  the 
sun  struggles  with  a  feeble  light. 

The  cirro-cumulus  presents  a  number  of  forms  and 
shapes,  and  is  sometimes  very  thin  and  fleecy,  then  in  dense, 
well-rounded  masses.  They  generally  arise  from  a  change 
in  the  cirrus  and  cirro-stratus,  and  then  fall  back  into  the 
same  forms.  This  class  of  clouds,  as  well  as  the  cirro-stra- 
tus, float  at  a  lofty  height,  next  to  the  cirrus. 

The  cumido-stratus  combines  the  features  of  the  two 
classes  after  which  it  is  named.  Its  base  generally  as- 
sumes the  form  of  the  stratus,  while  its  summit  resembles 
that  of  the  cumulus.  When  a  number  of  them  assumins: 
large  proportions  are  driven  together  by  the  winds,  they 
presage  the  approach  of  a  thunder-storm  ;  and  are  termed 
thunder-heads  by  the  common  people. 

The  Latin  term  nimbus^  meaning  dar'kj  rainy ^  has  been 
appropriated  as  the  name  for  the  rain-cloud.  When  first 
formed,  it  generally  assumes  a  dark,  threatening  aspect, 
especially  if  the  sun  shines  against  it.  This  changes  into 
a  grayisli  watery  appearance  when  the  rain  begins  to  fall. 
It  is  formed  from  a  combination  of  several  of  the  clouds 


80 


AGKICULTURAL  METEOROLOGY. 


described,  having  at  first  tiie  fringed  edges  of  the  cumulus 
type.  As  they  blend  together  and  increase  in  density, 
they  lose  their  simple  forms  and  merge  into  the  well-defined 
rain-cloud,  so  easily  distinguished  from  all  others. 

The  morning  rain-clouds  generally  come  from  the 
cumulo-stratus.  The  stratus  clouds  of  the  evening  pre- 
vious are  often  seen  lino-erino;  around  the  horizon  about 
sunrise,  assuming  the  cumulo-stratus  form,  and  tlien,  be- 
coming thicker  and  darker,  change  to  the  nimbus,  which 
soon  precipitates  in  showers  of  rain.  The  afternoon  show- 
ers, especially  during  summer,  originate  in  vapors  which 
rise  from  the  heated  lower  strata  of  air,  forming  at  first 
cumulus  clouds,  and  then  changing  into  nimbus. 

The  study  of  clouds  is  of  interest  to  the  practical  agri- 
culturist, as  they  indicate  the  approach  of  rain ;  and  he  may 
often  tell  by  their  appearance  a  day  or  two  in  advance, 
what  the  changes  in  the  weather  are  likely  to  be. 

Clouds  are  not  simply  useful  as  the  harbingers  of  rain, 
but  their  shade  often  saves  the  tender  plants  from  the 
burning  sun,  and  prolongs  their  existence  during  the  days 
of  protracted  drought. 

53.    Causes  of  Rain. 

There  are  several  causes  which  operate  in  the  conden- 
sation of  vapor  into  drops  of  water,  as  mentioned  by  Prof 
Graham. 

1.  The  ascent  of  the  heated  air  from  the  earth,  and 
consequent  rarefaction,  which  produces  cold.  This  is  ob- 
served frequently  on  the  summits  of  mountains,  where 
clouds  and  mists  appear  to  settle  and  remain  stationary; 
the  wind,  passing  over  the  plain  below,  strikes  the  moun- 
tain and  ascends,  producing  the  effect  mentioned. 

2.  The  mixing  of  hot  and  cold  currents,  both  saturated 
with  humidity,  first  demonstrated  by  Dr.  Hutton,  that  two 
volumes  of  air  thus  mixing  and  attaining  a  mean  tempera- 
ture are  incapable  of  sustaining  the  same  amount  of  vapor. 


CAUSES  OF  EAIX. 


81 


3.  The  contact  of  air  in  motion  with  the  cold  surface  of 
the  earth.  This  is  the  most  usual  cause  of  its  coldness  and 
condensation  of  vapors,  and  consequently  precipitation  of 
rain. 

To  illustrate  :  the  air  being  at  a  temperature  of  34°,  at 
Avhich  it  frequently  stands  in  the  winter-time  even  in  this 
climate,  a  southwest  wind  setting  in  will  cause  it  to  rise 
20°  in  36  or  48  hours.  Now  this  air,  being  probably  satu- 
rated with  humidity  at  54°  on  its  first  arrival,  mingling  with 
the  current  at  34°,  would  produce  a  condensation  of  the 
vapors  and  precipitation  of  rain.  Graham  illustrates  it 
thus : 

Tension  of  vapor  at  54°  0.429  inch. 

34°  0.214 

Condensed  0.215  " 

The  following  illustration  by  Prof.  Brocklesbey  is  to 
the  point :  "  Four  thousand  cubic  inches  of  air  at  the  tem- 
perature of  86°  F.  can  contain  no  more  than  31-2-  grains  of 
moisture,  and  an  equal  volume  at  32°  only  7|-  grains.  Now 
if  the  two  volumes  are  mingled  together,  their  average 
temperature  will  be  59°,  and  the  weight  of  moisture  they 
unitedly  possess  will  be  39f  grains.  But  at  this  tempera- 
ture 31-2-  gi'ains  is  all  the  moisture  that  8,000  cubic  inches 
of  air  can  possibly  retain  ;  since  the  first  portion  by  its 
union  with  the  second  diminishes  its  capacity  one-half, 
Avhile  that  of  the  latter  is  only  doubled.  The  excess  there- 
fore of  grains  will  be  condensed  and  descend  in  the  form 
of  water." 

This  condition  of  things  grows  out  of  a  law  of  nature 
by  Avhich  the  capacity  of  the  air  for  moisture  increases  at 
a  faster  rate  than  the  temperatui-e  :  the  latter  advancing 
arithmetically,  the  former  by  geometrical  progression. 

Rain  will  happen  often er  where  the  w^inds  are  variable 
and  shifting,  as  they  are  the  natural  agents  by  which  the 
combinations  of  cold  and  warm  air  are  effected.  Constant 
4* 


82 


AGRICULTURAL  METEOROLOGY. 


winds  blowing  for  a  long  period  over  an  atmosphere  of 
uniform  temperature,  as  the  deserts  of  Sahara,  will  never 
bring  rain,  until  they  meet  with  some  object,  as  the  slope 
of  a  mountain,  to  change  the  current  and  mix  the  hot  air 
with  the  cold. 

After  a  general  fall  of  rain,  the  atmosphere  is  clear  and 
unclouded,  and  comparatively  free  from  watery  vapor  ; 
there  is  also  less  heat  generated,  and  of  course  the  temper- 
ature is  cooler.  When,  however,  evaporation  begins  to 
take  place,  the  warmth  of  the  air  increases  as  well  as  its 
humidity. 

A  cold  and  warm  current  of  air  meeting  would  only 
form  clouds  or  fogs  at  first;  but  when  the  atmosphere 
becomes  so  full  of  humidity  as  to  approach  saturation,  the 
overplus  of  the  two  currents  would  be  converted  into  rain 
by  their  not  being  able  to  hold  the  same  amount  of  mois- 
ture when  combined,  for  reasons  before  stated. 

Vapors  rising  from  the  surface  of  the  ocean,  are  con- 
densed in  the  upper  and  cooler  regions  of  the  atmosphere, 
and  carried  by  the  winds  to  different  parts  of  the  earth, 
being  a  prolific  source  of  rain  over  the  continents.  The 
heated  air  which  ascends  at  the  equator  especially,  is  satu- 
rated with  moisture  in  passing  over  the  Northern  and 
Southern  oceans  ;  and  as  it  ascends  higher  and  spreads 
over  the  temperate  zones,  and  meets  with  colder  currents 
of  atmosphere,  it  is  condensed  and  falls  in  extensive  rains 
over  vast  sections  of  the  earth. 

54.  Amoimt  of  Rain- fall  at  Different  Stations, 

As  air  becomes  more  humid  when  its  temperature  in- 
creases, it  is  natural  to  infer  that  there  would  be  more 
rain  in  the  tropics  than  toward  the  poles.  This  is  not 
merely  theoretically  true,  but  has  been  established  by  facts  ; 
as  the  rain  kept  at  seven  stations  beginning  at  Grenada, 
at  IS''  north  of  the  equator,  and  ending  at  Uleaburg,  65^ 


AMOUNT  OF  EAIX-FALL. 


83 


north  latitude,  showed  a  gradual  falling  off  in  the  quantity. 
At  the  first  station  it  was  126  inches,  at  the  next  120,  then 
81,  39,  25,  15,  and  at  the  last  13|  inches.  Notwithstand- 
ing this  uniformity,  however,  there  are  great  differences  in 
the  same  latitude  owing  to  local  causes. 

At  San  Luis,  Maranham,  2°  30'  south  latitude,  the 
annual  fall  of  rain  has  reached  as  high  as  280  inches.  At 
Vera  Cruz,  Mexico,  278  inches  fell  in  one  year. 

The  heaviest  rainfall  on  record  occurred  at  the  Hima- 
laya mountains  :  660  inches  in  one  year. 

The  average  fall  at  Athens,  Georgia,  for  five  years,  kept 
by  Prof.  McCay,  was  37.53  inches  ;  while  at  Augusta  during 
the  same  period  it  was  40.27  inches.  This  difference  may 
be  accounted  for  in  part  from  the  lower  altitude  of  Augusta, 
being  160  feet  above  tidewater,  and  Athens  782. 

At  Sparta,  Georgia,  550  feet  altitude,  the  average  fall 
for  five  years,  kept  by  the  authoi',  ending  in  1869,  was  57.49 
inches.  In  1868,  the  largest  amount  recorded  in  any  one 
year,  the  rain-fall  was  78.32,  while  the  next  year  it  was  not 
half  so  much,  being  only  37.43  inches.  The  heaviest  fall 
for  one  month  was  in  August,  1867,  being  17.15  inches. 

There  seems  to  be  two  sliding  scales  for  the  year  in  this 
climate,  one  embracing  the  four  crop  months,  of  which 
August  is  the  climax.  Thus,  the  average  fall  for  the  five 
years  at  Sparta  was  for  May  3.38  inches,  June  3.52,  July 
4.29,  August  7.04.  There  was  also  a  regular  scale  for  the 
eight  cooler  months,  April  being  the  climax,  thus:  Sep- 
tember 2.61,  October  3.47,  November  3.77,  December  4.79, 
January  5.22,  February  5.46,  March  6.65,  and  April  7.54. 

Prof.  Phillips  found  that  a  very  moderate  elevation 
would  affect  the  fall  of  rain.  Thus,  on  the  top  of  York 
Minster,  242  feet  high,  the  annual  rain-fall  was  15.910 
inches.  On  the  roof  of  the  Museum,  73  feet  in  height, 
20.461  inches.  On  the  surface  of  the  ground,  24.401  inches. 
This  would  seem  to  indicate  that  rain  is  produced  mostly 


84 


AGKICULTUK AL  M  ETE OROLOG  Y. 


by  the  last  cause  mentioned  :  viz.  that  the  strata  of  air  near 
the  ground  being  more  rapidly  cooled  could  deposit  more 
humidity. 

55.   The  Rain  Gauge, 

The  Rain  Gauge,  or  Pluviometer,  is  the  instrument  used 
for  measuring  rain.  Any  vessel  Avith  perpendicular  sides, 
set  out  in  an  open  sj^ace  where  the  rain  might  fall  into  it 
would  indicate  the  amount  by  measuring  its  depth  with 
a  rule.  But  this  would  not  be  an  exact  method,  es|)ecially 
for  small  showers. 

In  order  to  do  this,  we  have  a  cylindrical  zinc  funnel, 
which  is  set  out  in  the  open  weather,  day  and  night,  and 
catches  all  the  rain  that  falls,  conveying  it  into  a  vessel 
beneath.  After  a  rain,  the  water  thus  caught  is  poured 
into  a  graduated  glass  tube  several  feet  long  and  several 
inches  in  diameter,  which  has  been  graded  to  the  circum- 
ference of  the  zinc  funnel.  When  the  water  rises  to  100  on 
this  graduated  tube  it  indicates  one  inch,  so  that  the  one- 
hundredth  of  an  inch  can  be  easily  estimated  by  it. 

liegular  observations  kejDt  by  this  instrument  in  a  given 
locality  may  be  made  very  useful  in  practical  fjirming. 
It  is  difficult  always  to  tell  whether  rain  enough  has  fallen 
upon  the  crop  from  mere  observation.  This  instrument 
gives  the  amount  with  mathematical  precision,  and,  other 
things  being  equal,  will  indicate  whether  a  sufficient  quan- 
tity has  fallen  for  a  good  season.  This,  how^ever,  is  very 
variable,  one  crop  requiring  more  than  another,  and  so  of 
different  classes  of  soils.  Much  less  rain  also  will  answer, 
when  it  falls  at  night  or  late  in  the  evening,  than  during  the 
morning  or  at  noon,  when  the  hot  sun  shines  down  upon 
it,  producing  rapid  evaporation. 

Rains  that  fall  at  night  cannot  be  w^ell  estimated  as  to 
their  amount;  and  yet  much  depends  ujDon  knowing  this 
fact  as  indicative  of  the  proper  work  of  the  day,  Avhether 
to  plough  or  hoe,  or  engage  in  other  work  :  with  the  rain 
gauge,  this  fact  is  easily  ascertained. 


SOURCES  OF  HAIN, 


85 


From  observations  made  during  a  series  of  years,  vre 
found  that  a  half  inch  of  rain  will  suffice  for  cotton  when 
it  begins  to  suffer,  while  corn  requires  three-fourths  to  an 
inch,  and  sv/eet  potatoes  still  more  than  this.  Land  that 
has  been  subsoiled,  needs  much  less  rain  than  common 
plough  land,  and  its  effects  will  last  longer  by  the  rising 
of  capillary  water  through  the  porous  subsoil. 

Observations  of  the  rain-fall  and  other  meteorological 
phenomena  compared  with  the  crop  production,  would 
form  a  pleasant  recreation  to  the  agriculturist,  and  kept 
for  a  series  of  years,  would  not  only  prove  of  benefit  to 
himself  and  his  section,  but  add  sometlnng  to  the  progress 
of  agricultural  science. 

56.   Sources  of  JRain, 

Most  of  the  heavy  summer  rains  which  fall  in  the  Cotton 
States  are  doubtless  generated  by  the  heated  waters  of  the 
Gulf  of  Mexico,  which  always  contain  so  much  heat  that 
tliey  give  off  an  immense  amount  of  vapor,  which  spreads 
for  many  miles  over  the  continent.  Thus,  when  a  southerly 
wind  sets  in  and  blows  for  36  or  48  hours,  we  are  almost 
sure  to  have  rain. 

It  is  different,  however,  with  our  Avinter  rains,  owing  to 
the  difference  in  the  temperature  between  the  land  and 
ocean.  In  cold  weather  they  are  more  general,  lasting 
frequently  for  several  days,  and  extending  over  a  large 
scope  of  country.  They  are  mostly  from  the  east,  showing 
that  they  originate  from  the  Atlantic  Ocean. 

In  summer,  the  Gulf  of  Mexico  condenses  moisture 
much  more  rapidly  than  the  ocean,  owing  to  the  greater 
heat  of  the  air  above  it;  while  in  winter,  the  land  being 
generally  colder  than  the  water,  there  is  no  cause  for 
southerly  winds  or  rains  from  that  quarter.  The  colder 
atmosphere  of  the  ISTorth  Atlantic  and  Avarmer  waters  of 
the  Gulf,  mingling  on  our  coast,  produce  condensation 


86 


AGEICULTUPvAL  METEOEOLOGY. 


and  rain,  and  as  the  atmosphere  becomes  colder  than  that 
of  the  land,  easterly  winds  set  in,  and  drift  the  rain  clouds 
over  the  continent. 


CHAPTEE  IV. 

OF  ELECTRICITY.  SUNLIGHT.  AIR  IN  MOTION.  LUNAR 

INFLUENCE. 

57.  Electricity. 

Electricity  at  one  time  was  thought  to  be  greatly 
instrumental  in  the  germination  of  seeds  and  the  growth 
of  plants.  The  old  idea  that  turnips  sown  at  particular 
changes  of  the  moon  would  do  better  than  at  other  times, 
has  been  accounted  for  on  the  supposed  electrical  condition 
of  the  moon  and  earth  at  those  particular  phases. 

It  is  known  that  nitric  acid  is  produced  during  thun- 
der-storms by  electricity,  and  believed  to  form  a  nitrate 
with  the  amm-onia  of  the  atmosphere,  which  falling  to  the 
earth  either  with  the  rain  water  or  by  its  own  gravitation, 
aids  to  a  small  extent  the  growing  summer  crops.  Ozone, 
also  believed  to  be  a  powerful  agent  in  vegetable  germina- 
tion especially,  is  generated  by  electricity. 

Davy  found  that  corn  sprouted  much  more  rapidly  in 
w^ater  positively  electrified  by  the  voltaic  instrument,  than 
when  in  a  negative  state.  As  water,  when  evaporated  from 
the  earth,  as  well  as  condensed  into  rain,  becomes  posi- 
tively electrified,  it  is  probable  that  this  condition  is  one 
reason  why  rain  water  is  so  much  better  a  fertilizer  tlian 
fountain  water. 

From  experiments  of  Pouillet,  it  appears  that  when 
seeds  first  sprout,  plants  become  positively  electrified, 
leaving  the  earth  in  a  negative  state.    The  same  results 


SUXLIGHT. 


87 


might  possibly  occur  during  the  growth  of  the  plant.  It 
is  well  known  that  the  vegetable  kingdom  suj)plies  the 
air  with  a  large  amount  of  electricity.  It  rises  with  the 
carbonic  acid  which  exhales  daring  the  night  from  all  grow- 
ing plants. 

M.  Becquerel,  the  elder,  states  that  the  atmosphere 
and  earth  are  constantly  in  two  dissimilar  states  of  elec- 
tricity;  the  former  having  an  excess  of  positive  electricity, 
the  latter  of  negative.  These  two  excesses  becoming 
neutralized  by  means  of  the  conducting  substances  found 
at  the  surface  of  the  earth,  especially  plants;  colored 
vegetable  tissues  are  affected  by  electrical  discharges  in  a 
peculiar  manner,  producing  three  distinct  actions  upon  the 
colors  of  leaves  and  flowers  of  plants:  First,  the  color- 
ing matters,  which  are  in  a  state  of  solution  in  the  cellules 
are  easily  absorbed  or  filtered  in  cold  water  after  being 
electrized.  This  is  particularly  true  of  red  and  blue 
colors.  Second,  when  the  electrization  is  prolonged  a  dis- 
coloring action  is  produced  on  those  colors  in  the  plant. 
Third,  infiltration,  or  a  transfer  of  the  coloring  matter 
takes  place  under  the  preceding  influences. 

It  would  thus  seem  that  electricity  has  much  to  do  with 
colorization  in  plants,  which,  as  is  well  known,  is  closely 
connected  with  their  health  and  growth. 

58.  Sunlight, 

The  influence  of  light  upon  vegetation  is  a  fact  well 
known  for  centuries.  Plants  growing  in  the  shade,  under 
trees  or  in  inverted  vessels,  are  recognized  by  the  most 
careless  observer  as  being  inferior  in  general  appearance, 
more  diminutive,  and  of  a  lighter  green  color  than  others. 
In  fact,  some  plants  cannot  long  survive  without  direct 
sunlight. 

In  1873  we  fixed  a  movable  cover  with  three  planks, 
and  placed  it  over  a  section  of  a  row  of  cotton,  after  it  had 


88 


AGRICULTURAL  METEOROLOGY. 


begun  to  leaf,  so  as  to  exclude  from  it  the  direct  rays  of 
the  sun.  It  was  not  removed  for  three  weeks,  except  to 
receive,  in  common  with  the  other  plants,  the  showers  of 
rain.  It  began  at  once  to  weaken  and  shrivel  up,  and  soon 
ceased  to  grow,  and  one  after  another  the  leaves  died  and 
fell  off  the  stalks,  and  at  the  end  of  the  time  above  speci- 
fied every  plant  was  literally  dead. 

Ingenhouz  and  Sennebier  found  that  seeds  germinate 
quicker  in  the  absence  of  light.  Bertholin  attributed  this 
to  deficient  moisture,  as  sunlight  would  cause  it  to  evapo- 
rate. Sennebier,  however,  conducted  some  exact  experi- 
ments, adding  more  moisture  to  the  plants  in  sunlight, 
and  arrived  at  the  same  conclusion  as  before. 

Saussure  contended  that  the  heat  associated  with  the 
light  retarded  germination,  and  when  this  was  obstructed, 
light  had  no  appreciable  influence  over  germination.  This 
seems  now  to  be  the  conclusion  of  modern  scientists. 

Late  experiments  appear  to  establish  the  fact  that  it 
is  necessary  to  exclude  seeds  from  the  luminous  rays  of  the 
solar  spectrum  in  order  for  their  healthy  germination  ; 
while  the  chemical  or  actinic  rays  are  indispensable  to  the 
process.  As  these  latter  penetrate  much  deeper  into  the 
soil  than  the  luminous  rays,  both  of  these  ends  may  be  ob- 
tained by  planting  seed  a  proper  depth  in  the  earth.  Seeds 
then  do  not  fail  to  grow  when  buried  too  deeply,  for  the 
lack  of  oxygen  simply,  but  also  because  of  the  exclusion 
of  the  chemical  rays. 

Solar  light  affects  the  direction  of  plant  growth.  If 
you  place  plants  in  a  window  they  instinctively  turn  to 
the  light,  and  seem  to  grow  more  rapidly  in  ihat  direction, 
as  if  they  received  more  nourishment  from  that  source. 
Knight  observed  that  branches  of  trees  shaded  by  others 
did  not  flourish  like  those  enjoying  more  sunlight.  This 
may  be  seen  in  roads  passing  through  forests  ;  the  limbs  of 
the  trees  extending  over  the  road  are  much  more  vigorous, 


AIR  IN  MOTION". 


89 


and  grow  larger  than  those  on  the  forest  side.  In  some 
instances,  as  the  ivy  and  mistletoe,  they  turn  from  the  light. 
The  young  stems  of  nasturtium  incline  to  it,  the  old  ones 
turn  from  it. 

Priestley  first  investigated  the  chemical  action  of  sun- 
light on  vegetation.  It  is  now  very  satisfactorily  ascer- 
tained by  chemists  that  carbonic  acid  gas,  being  absorbed 
from  the  atmosphere  by  the  leaves,  is  decomposed  by  sun- 
light, the  oxygen  emitted,  and  the  carbon  appropriated  to 
the  building  up  the  structure  of  the  plant.  More  of  this 
hereafter. 

59.  Air  in  Motion. 

It  is  proper  to  say  someting  of  the  icind^  air  in  motion^ 
as  it  in  several  ways  comes  within  the  scope  of  agricul- 
tural meteorology.  Anything  which  disturbs  the  repose 
of  the  atmosphere,  as  the  fall  of  an  avalanche,  may  be  con- 
sidered a  cause  of  wind.  A  change  of  temperature,  and  by 
consequence  of  density,  is  the  usual  cause.  Rarefication 
of  atmosphere,  produced  by  heat,  will  cause  the  contiguous 
column  of  cooler  air  to  flow  into  the  rarefied  column,  and 
thus  wind  is  induced. 

The  old  theory  that  magnetism  and  electricity  were  the 
principal  causes  of  the  currents  has  been  exploded.  The 
latter  has  doubtless  something  to  do  with  them,  but,  accord- 
ing to  Prof.  Henry,  is  more  a  consequence  than  a  cause. 
It  has  been  well  established  that  terrestrial  magnetism 
does  not  afi*ect  materially  meteorological  phenomena.  The 
air,  not  being  naturally  magnetic,  of  course  could  not  de- 
velop that  power  until  magnetized. 
'         The  true  theory  of  the  currents  of  wind,  as  first  estab- 
lished by  Prof.  Espy,  is  that  they  are  owing  to  the  amount 
of  heat  generated  by  the  condensation  of  vapor  into  rain. 
This  process  in  the  equatorial  regions  evolves  an  astonish- 
I    ing  power  in  the  form  of  heat,  as  the  vapor  condenses  and 
^    ascends.    The  impulse  given  by  the  solar  rays  to  the 


90 


AGRICULTURAL  METEOROI-OGY. 


atmosphere  is  the  remote  cause  of  its  agitation.  These 
doubtless  produce,  through  secondary  causes,  the  moving 
currents,  from  the  gentle  breeze  to  the  violent  storm. 

From  data  well  substantiated  by  experiments,  it  has 
been  proven  that  every  cubic  foot  of  rain  which  falls  on 
the  surface  of  the  earth,  leaves  in  the  air  Avhen  it  descends 
heat  enough  to  produce  an  expansion  of  at  least  6,000  cubic 
feet  in  the  space  of  the  surrounding  atmosphere,  beyond 
that  occupied  by  the  vapor  itself.  (Henry.) 

Counter  currents  are  constantly  going  on  in  nature  on 
a  large  scale,  like  those  illustrated  by  Franklin  between  a 
cold  and  warm  room.  A  door  opened  between  them  will 
show  by  a  lighted  candle  that  the  current  flows  into  the 
warm  room  from  below,  and  out  of  it  from  above.  Thus 
we  frequently  see  clouds  blown  by  currents  above,  directly 
oj)posite  to  the  wind  on  the  surface  of  the  earth. 

The  velocity  of  the  wind  is  estimated  by  an  instrument 
called  the  anemometer.  It  is  simply  a  small  windmill,  to 
which  is  attached  an  index,  by  which  the  number  of  revo- 
lutions per  minute  is  noted.  It  may  be  graduated  thus  : 
One  of  these  instruments  taken  on  a  still  day  on  a  raih'oad 
car  going  at  the  rate  of  twenty  miles  an  hour,  and  the 
number  of  revolutions  counted  and  divided  by  60,  will  give 
its  velocity  per  minute.  The  higher  aerial  currents  may  be 
estimated  by  the  speed  with  which  the  shadow  of  a  cloud 
passes  over  the  earth's  surface. 

Winds  may  be  properly  divided  into  three  classes  :  con- 
stant, periodical,  and  variable.  The  trade  loiiid  is  the  most 
remarkable  instance  of  the  first  class.  The  monsoons  and 
sea  breezes  are  periodical  winds.  Northwestern  winds 
generally  indicate  clear  weather  ;  southern  and  southwest- 
ern, foul  weather.  Easterly  winds  are  generally  damp  and 
not  good  for  invalids.  They  prevail  mostly  in  the  fall  and 
winter,  and  are  accompanied  with  long  spells  of  rain.  Gen- 
erally when  the  wind-vane  settles  due  north,  a  calm  ensues. 


LUNAR  INFLUENCE. 


Winds  veer  from  north  to  east,  south,  and  west :  very  rarely 
do  they  ever  change  in  a  westerly  direction. 

Cold  winds  in  the  spring-time  are  very  damaging  to 
young  cotton  and  other  plants  ;  and  during  the  summer, 
crops  are  seriously  injured  by  being  twirled  about  by  vio- 
lent gusts  of  w^ind.  In  autumn  much  cotton  is  destroyed 
by  being  blown  out  when  open,  daring  rain-storms.  Winds, 
however,  have  their  agricultural  uses:  they  enable  the  far- 
mer to  plough  much  sooner  after  long  spells  of  rain,  pre- 
vent killing  frosts  of  cold  nights,  and  add  to  the  health, 
vigor,  and  muscular  power  of  laborers  during  our  long,  hot 
summers. 

Winds  also  prevent  the  settling  of  pestiferous  vapors 
in  cities  and  around  habitations,  wdiich  would  be  a  con- 
tinued source  of  the  most  malignant  diseases.  The  car- 
bonic oxides  are  deadly  poisons,  and  are  being  constantly 
generated  from  the  decay  of  animal  and  vegetable  sub- 
stances, and,  as  they  are  heavier  than  the  atmosphere,  tend 
to  settle  near  the  earth  during  calm  spells  of  weather. 
The  winds  dissipate  them,  and  j^i'event  disease  and  death. 

60.  Lunar  Influence. 

The  influence  of  the  moon  upon  the  germination  of 
seeds  and  growth  of  plants  has  been  believed  for  ages  past. 
If  it  has  such  a  powerful  attraction  for  the  waters  of  the 
ocean  at  certain  phases,  as  to  produce  the  tides,  might 
it  not  be  potent  in  other  respects  ?  And  as  it  is  clearly 
established  that  the  direct  rays  of  the  sun  have  such  a 
powerful  eiFect  on  vegetation,  as  that  some  plants  cease  to 
grow,  and  die  without  them,  might  not  the  reflected  light 
of  the  moon  have  a  similar  though  modified  effect  ? 

It  is  probable  that  exact  experiments  would  show  that 
the  electrical  conditions  of  the  moon  at  certain  periods,  as 
well  as  its  increased  light  when  at  its  full  and  its  decrease 
when  in  the  wane,  ]iave  a  marked  effect  on  vegetation, 


I 


92 


AGRICULTURAL  METEOROLOGY. 


As  to  lunar  influence  upon  the  weather,  although  many 
observations  have  been  taken,  no  satisfactory  conclusions 
have  been  reached.  Experiments  made  in  England  by 
Dr.  Laycock  as  to  the  amount  of  rain-fall  at  different 
phases  of  the  moon,  show  but  little  if  any  difference.  We 
instituted  similar  experiments  for  a  number  of  months  in 
Sparta,  Georgia,  with  like  results.  The  amount  of  rain  at 
new  and  full  moons,  at  each  of  the  quarters  as  well  as  the 
intermediate  days,  was  very  nearly  the  same. 

For  ten  years,  at  Montpellier,  in  France,  there  were  nine 
rainy  days  in  the  growing  to  eleven  in  the  waning  moon. 
At  Munich,  in  Germany,  this  was  reversed ;  the  number  of 
rainy  days  on  its  increase  being  845,  against  696  on  its 
decrease  ;  showing  that  local  causes  have  more  to  do  with 
rain  than  lunar  influence.  From  March,  1873,  to  April,  1 874, 
at  this  experimental  station  (Athens,  Georgia),  there  were 
55  rainy  days  on  the  increase,  and  50  on  the  decrease 
of  the  moon.  The  amount  of  rain,  however,  which  fell  on 
the  decrease  was  more  than  double  the  other,  being  30.16 
inches  against  14.71.  It  is  to  be  regretted  that  other  exi:>e- 
rimenters  did  not  note  the  amount  of  rain  as  well  as  the 
rainy  days. 

It  has  long  been  a  popular  belief  that  the  full  moon  in 
April  of  each  year  was  hazardous  to  vegetation  because 
of  frost.  Herschel  and  others  held  that  the  full  moon 
generally  brings  cool  weather  with  it.  This  has  been 
accounted  for  by  scientists  ui3on  the  fact,  that  at  the  full 
moon  the  earth  receives  not  only  the  sun's  heat,  but  the 
reflected  heat  of  the  moon  also;  and  as  it  is  known  that 
the  more  heat  existing  in  the  atmosphere  the  greater  the 
capacity  for  its  absorption,  it  is  reasonable  to  infer  that 
the  vapor  would  be  dissipated,  and  the  skies  rendered  clearer 
at  the  full  than  at  other  phases  of  the  moon.  Clear  and 
calm  nights,  then,  are  apt  to  bring  cool  mornings  during 
the  spring-time,  and  hence  frost  is  dreaded  by  gardeners 


LUNAR  INFLUENCE. 


93 


and  fruit-growers  about  the  full  moon  in  April,  as  the  last 
one  that  could  possibly  bring  cool  weather  with  it. 

M.  P.  Charbonnier  noticed  the  increased  growth  of 
cryptogamic  vegetation  on  the  sides  of  an  aquarium  dur- 
ing the  time  of  full  moon  :  it  being  much  more  luxuriant 
than  at  the  new  moon.  Other  observations  being  made,  it 
was  found  that  aquatic  vegetation  was  affected  favorably 
under  the  influence  of  lunar  light. 


PAET  IIL 
SOILS  AS  RELATED  TO  PHYSICS. 


CHAPTER  L 

the  earth. — the  rocks.  geology  of  georgia. 

formatio^nt  of  soils. 

61.   The  Earth, 

The  science  which  treats  of  the  earth  is  called  Geology. 
This  relates  to  its  physical  form  and  what  it  contains,  as 
loam,  sand,  clay,  bowlders,  solid  rocks,  and  the  fossils 
imbedded  in  them.  It  also  teaches  much  of  the  earth's 
history,  of  its  soils  and  minerals,  and  their  utility  to  man. 
Many  of  its  speculations  are,  however,  dubious,  and  its 
chronological  data  uncertain  and  unreliable.  Its  well- 
established  facts  corroborate,  in  a  remarkable  degree,  the 
divine  record  in  the  first  chapter  of  Genesis. 

One-fourth  of  the  earth  is  solid  land,  containing  about 
52,500,000  square  miles.  About  three-fourths  of  this  lies 
north  of  the  equator,  which  has  been  called  the  Land  Hemi- 
sphere, as  the  other  has  been  termed  the  Water  Hemi- 
sphere. 

The  surface  of  the  earth  has  been  divided  into  loidands 
ov  plains^  which  rise  less  than  1,000  feet  above  the  level  of 
the  sea  ;  and  plateaus  or  table  lanch^  which  rise  above  these 
another  thousand  feet  ;  and  mountains^  whose  altitude 
varies  from  2,000  to  29,000  feet,  the  height  of  Mount 
Everest,  the  tallest  peak  of  the  Himalayas. 


THE  ROCKS. 


95 


The  mean  height  of  the  land  surface  of  the  earth  is 
is  about  1,000  feet  ;  the  mean  depth  of  the  ocean  about 
15,000  feet.  The  highest  mountains  generally  lie  nearest 
the  deepest  oceans,  leaving  the  continents  basin-shaped. 
In  proportion  to  the  two  bodies,  an  orange  is  much  rougher 
than  the  earth.  The  highest  mountain  is  as  1  to  1,600,  or 
the  thickness  of  one  sheet  of  paper  to  1,600  sheets. 

The  temperature  of  the  earth  is  not  uniform.  The  sun 
affects  it  about  the  depth  of  100  feet.  For  every  50  feet 
below  that  the  temperature  rises  about  one  degree.  This 
would  reduce  the  whole  of  the  interior  of  the  earth  to  a 
molten  fluid,  leaving  a  crust  of  some  50  miles  in  thickness, 
but  for  counteracting  agencies. 

Recently  Prof.  Le  Conte  has  announced  an  opinion  that 
the  whole  theory  of  geology  must  be  reconstructed  upon 
the  basis  of  a  solid  earth. 

62.   The  Books. 

The  rocks  which  compose  the  earth  are  divided  into 
two  great  classes,  the  stratified  and  unstratified. 

Stratified  rocks  exist  in  layers  and  strata,  and  are 
termed  aqueous^  because  they  are  believed  to  have  origi- 
nated in  the  settling  of  sediment  at  the  bottom  of  rivers  and 
oceans. 

Unstratified  rocks  are  not  in  layers,  but  massive,  reg- 
ular, irregular,  or  crystalline,  according  to  the  minerals 
of  which  they  are  composed.  They  are  called  also  igneous^ 
as  they  appear  to  have  resulted  from  the  cooling  of  molten 
matter. 

The  Primary  or  lowest  rocks,  called  Plutonian,  doubt- 
less originated  from  fire,  and  existed  long  before  the  crea- 
tion of  organized  matter,  animal  or  vegetable. 

By  far  the  larger  portion  of  the  rocks  have  evidently 
been  dissolved  and  stratified  by  the  action  of  water.  The 
oldest  of  these  (though  more  recent  than  the  igneous)  have 


96 


SOILS  AS  RELATED  TO  PHYSICS. 


110  fossils,  and  doubtless  constituted  that  long  chaotic 
period,  when  "the  earth  was  without  form,  and  void 
(empty  of  inhabitants),  and  darkness  dw^elt  upon  the  face 
of  the  deep." 

lletamorphic  rocks  are  those  which  have  apparently 
been  acted  on  by  both  fire  and  water. 

Unstratified  rocks  maybe  classed  as  Granite,  Syenite, 
Greenstone,  Basalt,  Trachyte,  Amygdaloid,  and  modern 
Lavas. 

Stratified  rocks,  as  Gneiss,  Mica  Slate,  Clay  Slate, 
Hornblende  Slate,  Talcose  Slate,  Quartz  Rock,  Sandstone, 
Conglomerate,  and  Limestone. 

The  most  common  of  these  rocks  are  Granite,  Gneiss, 
Mica  Slate,  Clay  Slate,  Quartz  Rock,  Sandstones,  and  Lime- 
stones. 

The  principal  minerals  entering  into  them  are  Quartz, 
Mica,  Feldspar,  Oxide  of  Iron,  Carbonate  of  Lime,  Talc, 
Hornblende,  Tourmaline,  and  Epidote. 

Most  soils  are  composed  of  the  disintegration  of  rocks 
w^hich  underlie  them.  The  earth  was  probably  at  one 
time  a  molten  mass,  and  when  cooled,  a  solid  rock  without 
soil.  But  by  chemical  agencies  put  into  action  by  the 
great  Architect  of  the  Universe,  the  rocks  were  disinte- 
grated and  rendered  soluble,  and  fitted  for  vegetable  life. 

The  character  of  a  soil  may  generally  be  determined 
by  the  rocks  which  underlie  it.  Thus,  if  lime  rocks  crop 
out,  the  soil  is  calcareous  ;  if  quartz  predominate,  it  is 
silicious,  and  so  on.  There  are  exceptions  to  this  rule, 
however,  as  the  coal-fields  of  some  countries,  and  most 
alluvial  soils ;  especially  the  deltas  of  large  rivers,  w^hich 
are  composed  of  the  debris  of  the  different  soils  through 
which  they  flow. 

The  depth  of  soils  on  the  surface  of  the  rocks  varies 
from  one  inch  to  two  hundred  feet.  Their  average  depth 
on  mountains  and  high  lands  is  much  below  that  on  plains 


GEOLOGY  OF  GEORGIA.  97 

and  in  valleys.  After  a  certain  de^Dtli  the  solid  rock  is 
always  found,  which  crops  ont  in  contiguous  places,  con- 
stituting mines,  quarries,  and  clilTs. 

63.    Geology  of  Georgia, 

The  geology  of  the  State  of  Georgia  may  be  stated 
thus  :  In  the  extreme  northwestern  counties,  extending  as 
low  down  as  the  Allatoona  Mountain,  we  have  the  older  fos- 
siliferous  rocks,  in  w^hich  are  the  petrified  remains  of  species 
of  shell-fish  long  since  extinct,  showing  that  coral  reefs  once 
existed  in  these  now  elevated  regions,  which  w^ere  then  the 
bottom  of  the  ocean.  In  this  same  region  the  carhonifer- 
ous  system  crops  out  to  a  small  extent.  Here  coal-beds 
exist. 

Then  comes  the  Primary  region,  extending  from  the 
Tennessee  line  down  the  Savannah  River  to  Augusta,  thence 
southwest  to  Columbus.  Thence  up  the  Chattahoochee 
River  to  near  Cedartow^n,  and  easterly  to  Canton  and  north- 
erly to  the  junction  of  the  Tennessee  and  North  Carolina 
line.  The  north v>^estern  belt  of  this  extensive  system  con- 
stitutes the  Gold  region,  and  a  narrow  strip  running  south- 
Avesterly  through  Habersham,  Hall,  and  Gwinnett  counties, 
forms  the  elastic  sandstone  (itacolumite),  which  is  regarded 
as  the  matrix  of  the  diamond. 

All  this  vast  region  is  Primart,  except  a  few  spots  in 
Gilmer,  Hall,  and  Habersham  counties,  where  the  blue 
limestone  crops  out,  and  very  good  marble  has  been  quar- 
ried. Most  of  this  region  is  underlaid  by  stratified  rocks, 
as  micaceous,  fel spathic,  and  syenite  gneiss,  and  talcose 
and  hornblende  schist.  Granite  ledges,  which  are  unstra- 
tified  and  crystalline,  crop  out  on  the  lower  border  in 
Hancock  and  other  counties,  and  again  in  De  Kalb,  as 
presented  in  the  majestic  Stone  Mountain. 

The  Cretaceous  system  embraces  several  counties  and 
parts  of  counties,  forming  a  triangle  between  Columbus 
5 


98 


SOILS  AS  RELATED  TO  PHYSICS. 


and  Knoxville,  and  the  mouth  of  Pataula  Creek  on  the 
Chattahoochee  River,  several  miles  above  Fort  Gaines. 
Again  it  occurs  in  a  small  place  near  Sandersville,  where 
clypeasters  and  shark's  teeth  are  found. 

All  the  lower  portion  of  the  State  not  described  belongs 
to  the  Tertiary  system,  and  presents  some  interesting  fea- 
tures as  to  its  fossils.  The  rocks  are  mainly  sandstones, 
with  rotten  limestone,  silicified  shells  and  buhrstone,  which 
makes  good  millstones  for  grinding  corn.  The  soil  is 
silicious,  and  in  some  places  marly  ;  not  rich  in  potash  like 
the  middle  belt,  except  in  sections  which  have  a  clay  sub- 
stratum. This  really  constitutes  some  of  the  best  cotton 
lands  in  the  State. 

Yast  sections  (embracing  a  number  of  counties  in  this 
region  generally  known  as  the  wire-grass),  are  composed  of 
a  silicious  soil  deficient  in  important  elements  and  covered 
in  many  j^laces  by  stunted  pines. 

Generally  in  this  Tertiary  region,  the  lands  are  valu- 
able where  the  pines  are  large;  as  the  spines  of  these  trees 
abound  in  potash,  which  has  been  brought  up  as  the  work 
of  ages,  by  their  tap  roots  from  the  subsoil  beneath,  and 
spread  upon  tlie  surface  to  form  a  rich  loam,  as  they 
accumulate  and  decay. 

The  underlying  rocks  in  this  section  are  devoid  of 
potash  ;  hence  this  substance  must  have  come  from  the 
Primary  region  above,  and  the  organic  remains  of  the 
marine  animals  which  inhabited  the  vast  Eocene  sea  once 
covering  it. 

64.  Disintegration. 

The  term  waste  has  been  applied  by  chemists  to  the 
effects  of  mechanical  forces  upon  rocks,  as  that  oi  disinte- 
gration is  said  to  denote  chemical  action. 

Disintegration  is  effected  by  oxygen,  carbonic  acid, 
and  water.  It  is  a  gradual  but  effective  process.  Perhaps 
in  the  lifetime  of  an  individual  but  little  is  accomplished. 


MECHANICAL  ACTION,  OR  WASTE. 


99 


yet  what  poets  call  the  "  tooth  of  time"  will  eat  its  way 
in  the  lapse  of  ages. 

Protoxide  of  iron  is  an  ingredient  of  many  of  the  com- 
mon rocks,  as  basalt  and  clay  slate ;  and  having  a  great 
tendency  to  absorb  oxygen  from  the  atmosphere  and  be- 
come converted  into  a  higher  oxide  known  as  the  per- 
oxide, by  this  process  the^e  rocks  are  gradually  broken 
down  and  become  converted  into  rich  ferruginous  soils. 

And  this  is  true  to  a  limited  extent  of  other  minerals,  as 
their  ingredients  are  susceptible  of  entering  into  union 
with  oxygen.  Thus  the  metallic  sulphurets  are  gradually 
converted  into  sulphates. 

The  decomposition  of  silica  from  its  alkaline  bases  is 
effected  by  the  action  of  carbonic  acid  and  water,  and  in 
this  way  many  rocks  as  (felspar,  containing  silicate  of  pot- 
ash) are  broken  down  and  converted  into  soil.  Large  beds 
of  porcelain  clay  (decomposed  felspar),  Avhich  are  found  on 
the  line  of  the  Primary  and  Tertiary  formations  of  South 
Carolina  and  Georgia,  have  been  thus  disintegrated  and 
mingled  with  the  soil. 

Water  seems  to  be  essential  to  the  proper  action  both 
of  oxygen  and  carbonic  acid  in  the  decomposition  of  rocks, 
although  it  is  difficult  to  say  exactly  what  that  action  is. 

The  influence  of  these  three  agents  upon  rocks  is 
clearly  seen  in  the  silver  mines  of  South  America,  which 
led  to  their  discovery  by  huntsmen  and  herdsmen. 

This  metal,  being  invulnerable  to  these  agencies,  while 
the  rocks  associated  with  it  have  been  dissolved  away, 
stands  out  in  tooth-like  proportions  in  many  instances  from 
the  surface  of  the  boAvlders  and  jutting  cliffs. 

65.  Mechanical  Action^  or  Waste. 

Mechanical  as  well  as  chemical  forces  are  constantly 
at  work  in  breaking  dowui  the  rocks  and  forming  soils. 
Rocks  are  thus  worn  by  glaciers,  snow-drifts,  and  i"ain- 


100 


SOILS  AS  RELATED  TO  PHYSICS. 


Storms;  and  immense  beds  of  their  debris  are  formed  in  the 
bottoms  of  rivers,  to  be  washed  out  by  the  floods,  forming 
rich  alluvial  lands. 

Extremes  of  heat  and  cold,  the  alternate  freezing  and 
thawing  of  water,  have  in  many  cases  much  to  do  with 
these  processes.  Dense  limestone  is  sometimes  acted  on 
by  the  frost  of  a  single  night  so  effectually  as  to  render 
turbid  the  waters  that  wash  over  it  the  next  day. 

Prof.  Agassiz  supposes  that  glaciers  of  ice  have  done 
more  to  grind  the  rocks  to  pieces,  and  thus  prepare  the  soil 
for  vegetation,  than  every  other  agency  put  together.  The 
stones  and  rocks  ground  and  polished  by  the  glaciers  are 
easily  distinguishable  from  those  scratched  by  running 
water.  The  angular  bowlders  found  in  meadows  and  ter- 
race of  rivers  not  reached  by  water  can  be  accounted  for 
only  in  this  way. 

CHAPTER  11. 

CLASSIFICATION  OF  SOILS,  GEOLOGICAL  AND  AGRICULTURAL. 

66.    Geo  log  ical  Div  Ision  of  So  Us. 

The  geological  division  of  soils  embraces  the  Sedentary 
and  Transported. 

Sedentary  soils  are  those  which  are  supposed  to  remain 
in  situ^  having  never  been  removed  by  geological  agencies. 
The  rocks  which  underlie  them  give  a  good  idea  of  their 
composition  and  agricultural  value.  This  class  of  soils 
usually  has  but  little  depth.  Most  of  the  soils  of  Middle 
Georgia  are  of  this  character. 

Transported  soils  are  those  which  have  been  drifted 
by  glaciers  or  floods  from  their  original  position,  and  de- 
posited as  sediment.  These  have  again  been  divided  into 
Drift,  iVUuvial,  and  CoUuvial  soils. 


AGRICULTURAL  DIVISION  OF  SOILS. 


101 


Drift  soils  are  generally  without  stratification,  and 
have  fragments  of  rocks  rounded  by  friction,  of  all  sizes 
from  small  pebbles  to  large  rounded  bowlders.  Geologists 
believe  that  these  drift  soils  were  formed  during  what  they 
term  the  Glacial  Epoch,  by  moving  bodies  of  ice.  There 
are  many  evidences  of  drift  soil  in  the  counties  bordering 
on  the  Primary  and  Tertiary  regions  of  this  State. 

Alluvial  soils  are  simply  the  deposits  of  running  waters, 
rivers,  and  tides.  They  are  more  or  less  stratified,  and  have 
no  large  masses  of  rocks,  as  currents  of  water  cannot  move 
them  any  great  distance.  These  deposits  are  formed  in 
every  land  and  during  every  period.  Valleys  contain  them 
drifted  down  from  mountains  and  hills.  Lakes  and  gulfs 
and  sometimes  seas  are  filled  with  silt  by  the  attrition  oi' 
ages,  and  recede,  leaving  alluvial  deposits.  The  lowlands 
and  deltas  of  all  rivers  and  running  streams  are  constantly 
forming  them  by  freshets  and  floods. 

Colluvial soils  consist  of  both  drift  and  alluvium,  have 
sharp  angular  fragments  of  rocks,  and  seem  to  have  been 
transported  bu,t  a  small  distance  from  their  original  posi- 
tion, if  not  formed  in  place. 

67.  Agricultural  Division  of  Soils, 

Soils  are  classified  agriculturally,  according  to  the  pre- 
ponderance of  certain  substances.  Thus,  w^here  silica  pre- 
vails, it  is  called  a  sandy  soil ;  where  alumina  abounds,  it 
is  a  clay  soil ;  the  preponderance  of  lime  gives  calcareous 
and  mar/y  soils  ;  of  organic  matter,  a  vegetable  mould  ;  and 
where  there  is  a  due  admixture  of  all,  a  loamy  soil. 

The  upper  crust  of  the  soil,  varying  from  an  inch  to  six 
or  eight  inches  in  depth,  is  called  the  surface  soil,  or  tiltJi^ 
wRich  is  stirred  by  the  plough,  and  acted  upon  directly 
by  the  chemical  agencies  of  the  atmosphere.  Here  seeds 
germinate  and  plants  send  out  their  roots  in  search  o\ 


102 


SOILS  AS  RELATED  TO  PHYSICS. 


food,  and  here  they  decay  and  blacken  the  soil,  being  con- 
verted into  humus. 

The  subsoil  is  the  stratum  immediately  beneath  the 
surface  soil,  or,  in  a  more  extended  sense,  all  that  underly- 
ing portion  of  the  soil  down  to  the  solid  rock  upon  which 
it  rests.  Tap-rooted  trees  and  plants  receive  much  of  their 
nourishment  from  this  substratum,  in  some  instances  for 
many  feet  below  the  surface. 

68.  Silicious  Soils. 

Sandy  or  silicious  soils  contain  from  70  to  90  per  cent, 
of  sand.  They  are  light  and  porous,  not  retentive  of  mois- 
ture, and  by  consequence  suffer  quickly  from  a  drought. 
They  do  not,  however,  possess  much  of  the  fertilizing 
elements,  are  more  easily  exhausted  of  them,  hence  wear 
out  much  sooner;  and  when  soluble  fertilizers  are  applied 
to  them,  they  leach  out  more  readily  by  the  heavy  spring 
rains.  They  are  much  more  friable,  permeable  to  water, 
and  easier  to  cultivate  than  clay  soils.  Deep  ploughing 
is  much  easier  achieved,  and  wider  ploughs  may  be  used, 
so  that  one  mule  can  cultivate  many  more  acres  of  land, 
and,  on  soils  equally  fertile,  with  more  profit. 

The  only  way  to  permanently  improve  such  soils  is  to 
add  clay  to  them,  which  will  not  pay  in  this  country, 
where  lands  are  so  cheap.  This,  however,  is  common  in 
Europe,  as  is  also  the  application  of  liquid  manures  to  this 
class  of  lands,  which  is  said  to  pay  well. 

69.    Clay  Soils, 

Clay  soils  are  cold  and  dense,  and  termed  "  heavy  " 
because  they  require  much  more  labor,  strength,  and  mo^ey 
to  cultivate  them  successfully  than  other  soils. 

Up  to  a  certain  percentage  the  retentive  quality  of 
clay  for  moisture  is  a  great  benefit.  By  this  quality  water 
is  held  and  let  off  slowly  to  plants  in  dry  weather,  and 


CALCAREOUS  SOILS. 


103 


ammonia  and  other  salts  retained  for  future  use.  Too 
much  clay,  however,  renders  the  soil  so  compact  and  re- 
tentive of  water  as  to  submerge  the  roots  and  cause  ob- 
struction to  nutrition,  as  well  as  to  prevent  proper  aeration. 
Such  soils  require  much  labor  to  j^lough,  and  are  apt  to 
break  up  in  clods. 

All  soils  which  have  a  pij^e-clay  substratum  are  of  this 
class,  and  in  this  country  are  generally  laid  aside  as  un- 
productive. Cotton  will  always  rust  upon  them,  from  the 
inability  of  the  tap  root  to  penetrate  and  find  proper  nour- 
ishment, and  corn  will  take  the  "  yellows,"  as  farmers  say, 
from  the  superincumbent  moisture. 

The  most  effectual  remedy  is  drainage,  which  costs  too 
much  for  our  cheap  lands.  Burning  and  liming  are  also 
used  to  advantage  in  the  old  countries,  where  it  will  pay 
to  reclaim  such  soils.  When  reclaimed  they  are  among 
the  most  fertile  of  all  soils,  and  will  last  longer  than  others, 
from  the  quantity  of  potash  and  other  mineral  food  with 
which  they  abound. 

70.   Calcareous  Soils, 

Calcareous  or  lime  soils  exist  extensively  in  many  sec- 
tions of  Europe  and  the  United  States,  but  are  not  very 
prevalent  in  the  South. 

All  soils  containing  twenty  per  cent,  and  more  of  car- 
bonate of  lime  are  classed  as  calcareous.  This  embraces 
every  degree  of  fertility,  from  the  character  of  the  rocks 
from  which  they  originate.  The  great  majority  are  classed 
as  thin,  poor  soils,  while  those  resting  on  the  lower  chalk 
formation  are  said  to  be  quite  fertile.  Lime  soils  are 
light  and  easy  to  work,  and  are  particularly  adapted  to 
clover,  peas,  and  other  leguminous  crops. 

Marly  soils  consist  of  a  due  admixture  of  clay  and 
lime,  and  their  qualities  are  intermediate  between  the  two 
— having  from  five  to  twenty  per  centum  of  lime.   They  are 


104 


SOILS  A3  RELATED  TO  PHYSICS. 


generally  quite  fertile,  owing  to  the  fact  that  they  have,  in 
addition  to  other  mineral  substances,  more  than  a  usual 
quantum  of  phosphoric  acid.  There  are  besides  clay  marls, 
chalk  marls  and  sandy  marls.  They  are  used  with  good 
effects  as  manures  on  other  classes  of  soils. 

71.    Vegetable  Moulds, 

Vegetable  moulds  embrace  soils  which  have  a  large 
quantity  of  organic  matter,  either  as  humus  or  in  some 
other  form.  Garden  soils  and  fresh  forest  lands  are  in- 
cluded in  this  variety— the  organic  matter  existing  from 
five  to  ten  per  cent.  These  are  classed  as  among  the  most 
fertile  of  soils. 

Peaty  or  boggy  soils  contain  frequently  a  much  larger 
amount  of  vegetable  matter,  sometimes  as  high  as  seventy 
per  cent.  This  renders  it  unproductive,  owing  to  the  gen- 
eration of  acids  and  the  absence  of  soluble  plant-food. 
Burning  and  liming  is  the  proper  treatment  for  the  reduc- 
tion of  such  soils. 

But  while  an  overplus  of  vegetable  matter  becomes 
injurious,  a  certain  percentage  is  always  requisite  to  make 
a  fertile  soil:  as  not  only  does  it  add  to  the  physical  im- 
provement of  most  soils  by  the  admission  of  air  and  the 
retention  of  moisture,  but  the  decomposition  of  vegetable 
debris  constantly  going  on,  keeps  on  hand  a  rich  supply 
of  soluble  food  for  plants. 

Loamy  soils  consist  of  a  mixture  of  sand,  clay,  lime, 
and  organic  matter,  and  they  rank  in  fertility  next  to  the 
fertile  vegetable  moulds.  They  are  subdivided  into  clay 
loams,  sandy  loams,  etc.  They  combine  most  of  the  ad- 
vantages of  every  other  class  of  soil,  without  their  dis- 
advantages, being  sufficiently  retentive  of  moisture,  with- 
out too  much  coldness — having  enough  clay  to  absorb  and 
retain  valuable  manures,  and  enough  sand  and  organic 
matter  to  make  the  land  friable  and  cultivation  easy. 


WEIGHT  OF  SOILS. 


105 


Some  soils  are  termed  ferruginous^  in  which  iron 
ahounds,  as  oxides  or  silicates.  They  are  brown,  red,  or 
yellowish  in  color. 

Gravelly  soils  are  termed  so  from  the  number  of  small 
stones  they  contain.  Soils  of  this  character,  however  rich 
in  mineral  food,  are  generally  infertile,  from  their  coarse- 
ness and  difficult  assimilation. 


CHAPTER  III. 

PHYSICAL  QUALITIES  OF  SOILS. 

72.  As  Distinguished  from  ChemicaL 

The  soil  is  possessed  of  both  physical  and  chemical  pro- 
perties. Its  physical  properties  are  very  important,  though 
subordinate  to  the  chemical.  They  relate  simply  to  the 
mechanical  condition  and  arrangement  of  the  visible  par- 
ticles of  the  soil,  to  each  other,  to  air,  Avater,  temperature, 
and  gravitation.  A  deficiency  in  physical  properties  will 
retard  vegetable  growth  and  minify  the  product  of  a  soil, 
but  still  perfect  plants  are  produced.  A  deficiency  in  chem- 
ical properties  is  fatal  to  the  very  existence  of  vegetation. 

73.    Weight  of  Soils. 

Different  kinds  of  soils  vary  in  weight.  A  cubic  foot 
of  dry  earth  of  diflferent  kinds,  according  to  Schubler,  will 


weigh  as  follows  : 

Silicious  or  Calcareous  earth. . .   110  lbs. 

Half  clay  and  half  sand  95  " 

Common  arable  land  80  to  90  " 

Pure  agricultural  clay  75  " 

Rich  garden  mould  70  " 

Peaty  soil  30  to  50  " 


Sandy  soils  will  weigh  something  over  4,000,000  lbs. 


106 


SOILS  AS  RELATED  TO  PHYSICS. 


per  acre,  a  foot  in  depth.  Clay  soils  less  this.  An  average 
of  arable  loamy  soil  will  be  about  4,000,000  lbs.  Sandy 
soils  are  termed  ^' light"  because  of  their  lack  of  adhesive 
qualities,  yielding  readily  before  the  plough  ;  and  clay  soils 
heavy  "  because  of  their  adhesive  qualities  and  resistance 
to  the  plough.  They  are  lighter  than  any  exce23t>  vegetable 
moulds.    These  are  light  in  both  senses. 

Sandy  soils  being  so  much  heavier  than  clay  soils, 
having  an  equal  percentage  of  nutritive  elements,  would 
have  a  more  fertile  tilth,  because  a  greater  number  of 
pounds  of  soil  in  the  same  depth. 

The  porosity  of  a  soil  has  much  to  do  with  its  weight. 
When  thd  air  is  excluded,  all  soils,  except  those  abound- 
ing in  humus,  have  nearly  the  same  density. 

The  specific  gravity  of  a  soil  is  its  weight  in  bulk,  com- 
pared to  the  same  bulk  of  water.  A  cubic  foot  of  water 
weighs  62|-  lbs. 

The  weight  of  soils  above  given  does  not  apply  to  solid 
soils,  but  relates  to  soils  in  a  natural  state,  including  the 
atmospheric  air  in  their  interspaces. 

74.  Absorptive  Power  of  Soils  for  Gases, 

Not  only  do  certain  soils  have  the  power  of  absorbing, 
but  at  the  same  time  of  condensing  gases  into  smaller 
spaces.    This  power  is  called  the  force  of  adhesion. 

Charcoal  affords  a  good  illustration  of  this  force,  ab- 
sorbing ninety  times  its  bulk  of  ammonia. 

Experiments  of  Reichardt  and  Blumtritt  show  that  100 
grains  of  moist  garden  soil  yielded  14  cubic  centimetres 
of  gas,  while  the  air-dried  yielded  38.  Nitrogen  is  nearly 
always  absorbed  in  greater  proportion  than  oxygen  by 
soils,  and  is  greatly  condensed  in  some  cases. 

A  fine  dry  soil  will  completely  absorb  all  the  offensive 
matters  of  human  ordure,  as  in  the  case  of  the  earth  closet 
now"  in  use  among  many  families.  Nothing  but  an  earthy 
amnioniacal  smell  appears  to  result  from  its  decomposition. 


POWER  TO  REMOVE  SALTS  FROM  SOLUTIONS.  107 


It  is  now  admitted  by  chemists,  that  but  little  volatile 
matters  escape  even  from  dung  scattered  over  the  surface 
of  the  earth,  so  powerful  is  its  absorbing  power  on  these 
gases.  Some  soils  possess  this  power  much  more  than 
others  ;  as  those  abounding  in  clay  and  humus,  while 
sandy  soils  have  it  only  in  proportion  to  the  percentage  of 
these  substances  present. 

From  a  series  of  experiments  instituted  by  Reichardt, 
the  following  conclusions  have  been  reached  as  to.  the 
power  of  soils  to  absorb  gases : 

1.  Clay  purified  by  hydrochloric  acid  and  dried  at  a 
temperature  of  212^,  absorbs  carbonic  acid  very  slightly 
when  compared  with  that  which  contains  hydrated  oxide 
of  iron. 

2.  Sand  treated  in  the  same  manner  absorbs  only  slight 
traces  of  carbonic  acid ;  and  so  of  mixtures  of  clay  and 
sand  in  a  dry  condition  :  but  much  larger  quantities  when 
in  a  moist  condition.  Moisture  favors  the  absorption  of 
nitrogen  rather  than  oxygen. 

Soils  lose  what  they  absorb  when  exposed  to  the  sun, 
and  gradually  regain  it  again  in  the  shade.  The  amount 
absorbed  is  very  small,  however,  in  all  the  soils  tried, 
except  that  containing  hydrated  oxide  of  iron,  which 
seems  to  add  much  to  the  absorptive  power. 

The  amount  of  carbonic  acid  in  a  soil  also  corresponds 
to  its  per  centum  of  this  oxide.  The  action  of  the  sun's  heat 
is  to  drive  out  a  large  part  of  the  carbonic  acid  existing 
in  all  soils,  especially  when  moist.  The  amount  of  car- 
bonic acid  is  less  of  an  evening,  owing  to  the  elFects  of  the 
sun,  and  more  of  a  morning,  as  the  soil  regains  it  during 
the  night. 

75.  Poirer  to  JRemove  Salts  fro^n  Solutions, 
The  power  of  soils  to  remove  salts  from  their  solutions 
is  a  remarkable  quality,  possessed  especially  by  simple 


108 


SOILS  Aa  RELATED  TO  PHYSICS. 


sand.  Lord  Bacon  referred  to  this  power,  known  even  in 
his  day,  in  which  holes  dug  in  the  sand  on  the  sea-shore, 
at  low  tide,  would  have  pure  fresh  water  at  high  tide  flow 
into  them. 

Dr.  Stephen  Hales  also  mentions,  that  sea  water  may 
be  made  pure  by  filtering  through  stone  cisterns ;  the  first 
being  quite  free  from  brackishness,  and  then  becoming 
gradually  as  salt  as  usual.  Berzelius  found  the  same  thing 
true  in  filtering  salt  water  through  sand ;  and  Matteuci 
found  similar  results  in  experimenting  with  other  salts. 

Thus,  while  sandy  soils  are  very  deficient  in  the  power 
to  absorb  and  hold  water  and  gases,  they  are  compensated 
somewhat  for  its  loss  by  possessing  the  power  to  remove 
solid  saline  substances  from  solutions,  which  otherwise 
would  be  wholly  lost  to  them  by  drenching  rains.  Heiden 
also  found  a  similar  quality  to  be  possessed  by  humus. 
Solutions  of  chloride  of  potassium  and  ammonium,  when 
brought  into  contact  with  peat,  were  thus  deprived  of  a 
portion  of  these  salts  and  made  perceptibly  weaker. 

Schumacher  also  found  that  prepared  humus  made  of 
sugar  absorbed  about  two  per  cent,  of  sulphate  of  soda  and 
ammonia,  about  four  of  sulphate  of  potash,  and  ten  of 
i:)hosphate  of  soda.  He  also  found  that  humic  acid,  satu- 
rated with  sulphate  of  ammonia,  would  be  replaced  by  sul- 
phate of  soda.  Free  water  would  readily  dissolve  the 
salts  of  the  humic  acid. 

Clay  and  humus  possess  this  power  in  a  remarkable 
degree  as  to  ammonia,  phosphoric  acid,  and  certain  nutrient 
salts  which  are  very  soluble  in  water. 

It  seems  that  the  finer  constituents  of  the  soil  possess 
this  property,  partly  by  capillary  attraction  and  partly  by 
chemical  transmission  and  exchange,  by  which  they  are 
rendered  less  soluble  in  water,  but  only  so  much  so  that 
they  can  only  be  extracted  again,  very  slowly,  by  the  long- 
continued  a''-tion  of  water. 


ADHESIVENESS  OF  SOILS. 


109 


On  this  principle  putrescent  and  offensive  liquids  are 
taken  up  when  filtered  through  a  soil,  especially  clay  and 
huraus  soils,  which  lose  their  fertility  more  slowly  than 
sandy  soils.  This  may  be  easily  demonstrated  by. filling  a 
jar  or  bottle,  having  a  small  hole  in  the  bottom,  with  fine 
river  sand  or  garden  earth:  pour  in  a  strong  lye,  made  by 
the  solution  of  stable  manure  in  water,  which  is  very  high 
colored  and  quite  offensive  to  the  smell  at  first ;  it  will 
trickle  out  below  perfectly  purified  and  sweet,  having  left 
all  of  its  offensive  matters  in  the  soil  contained  in  the  jar. 

76.  Adhesiveness  of  Soils, 

The  adhesiveness  of  a  soil  depends  to  a  considerable 
extent  on  its  dryness.  Thus  vegetable  moulds  and  sili- 
cious  and  calcareous  soils  have  very  little  adhesiveness 
when  dry,  but  considerable  when  in  a  moist  state. 

A  clay  soil,  when  thoroughly  dried  and  pulverized,  has 
but  little  adhesive  power,  and  scarcely  more  resistance  to 
the  plough  than  a  sandy  soil.  When  saturated  with  water 
it  runs  together,  and  becomes  very  hard  and  heavy  after 
drying  off.  It  is  difticult  to  plough,  and  breaks  up  in 
lumps,  requiring  repeated  harrowings  to  have  it  properly 
pulverized  for  the  planting  of  seed.  Particularly  is  this 
the  case  when  ploughed  too  soon  after  a  rain.  The  effect 
of  subsoiling  on  such  lands,  seemingly  important,  will  last 
but  a  short  time. 

In  Europe,  where  every  class  of  soil  is  worked,  they  use 
thorough  drainage,  deep  tillage,  and  the  application  of 
sand,  with  advantage.  The  same  purpose  is  accomplished, 
and  more  effectually,  by  burning,  as  practised  in  England, 
which  is  said  to  cause  the  clay  to  lose  permanently  its 
tenacious  quality.  Liming  and  the  incorporation  of  vege- 
table matter  also  have  a  good  effect  on  this  class  of  soils. 
The  freezing  and  thawing  of  water  in  the  soil  in  cold 
climates  has  a  fine  effect  in  separating  the  particles  and 


110 


SOILS  AS  BELATED  TO  PHYSICS. 


overcoming  its  adhesiveness.  As  water  expands  when  it 
solidifies,  a  great  jDower  is  thus  brought  to  bear  upon  it. 

Schubler  estimated  that  immediately  after  the  frost 
disappears  from  lands  in  spring-time,  there  is  one-third 
less  resistance  in  clay  loams  than  previously. 

One  advantage  of  fall  ploughing  is  that  the  frosts  of 
winter  have  a  better  effect  in  pulverizing  soils,  by  which, 
also,  more  nutrition  is  secured  to  plants  in  soluble  forms. 

The  absorbing  power  of  the  soil  seems  to  be  in  direct 
proportion  to  its  adhesiveness.  Sandy  soils,  possessing  this 
quality  in  a  less  degree  than  dry  soils,  do  not  hold  nutri- 
ent salts  so  tenaciously;  hence  practical  agriculturists  have 
learned  to  apply  soluble  manure  in  smaller  quantities  and 
more  frequently  to  such  lands,  as  it  will  not  pay  to  apply 
them  in  large  quantities,  as  upon  more  tenacious  soils. 

77.  Divisibility  of  Soils, 

The  divisibility  of  a  soil,  or  its  capability  of  being 
divided  into  coarser  or  finer  particles,  is  a  very  imj)ortant 
quality.  All  fertile  soils  have  a  large  percentage  in  an 
extremely  fine  condition.  This  not  only  causes  a  much 
greater  surface  to  be  exposed  to  the  fibrils  of  the  plant,  but 
also  to  solvents  both  of  the  atmosphere  and  soil,  by  which 
a  much  larger  amount  of  soluble  food  may  be  prepared. 
There  are  exceptions  to  this  rule,  where  soils  of  a  cemented 
structure  may  become  too  compact  from  their  extreme 
fineness. 

In  coarse,  gravelly  soils,  soluble  food  must  be  added  in 
order  to  insure  anything  like  remunerative  crops.  Land 
buyers  have  learned  the  unproductiveness  of  this  class  of 
soils,  and  always  avoid  them. 

The  importance  of  comparative  divisibility  in  soils  may 
be  illustrated  by  a  block  of  granite  on  which  mosses  and 
lichens  will  grow.  Broken  up  into  coarse  gravel,  a  higher 
order  of  weeds  will  spring  up  and  grow  ;  and  reduced  to 
a  fine  dust,  the  cereals  and  finer  plants  will  flourish  in  it. 


TEMPEEATURE  OF  SOILS. 


Ill 


YS.  Shr inking  of  Soils. 

The  shrinking  of  soils,  effected  by  their  becoming  dry 
after  heavy  rains,  as  well  as  by  frost,  thus  changing  their 
bulk,  is  a  matter  of  much  practical  import.  This  also 
pertains  mostly  to  clay  soils.  Thus  constant  changes  are 
going  on  ;  they  expand  when  wet  and  shrink  when  dry, 
presenting  in  some  cases  quite  a  cracked  surface. 

Heavy  clays  will  lose  one- tenth  of  their  volume  on  dry- 
ing, which  acts  injuriously  on  plants  by  rupturing  the 
rootlets  in  long  dry  spells,  thus  adding  to  the  severity  of 
the  drought.  In  this  respect  sandy  soils  have  an  advan- 
tage, as  they  do  not  cake  or  shrink  by  wet  and  dry  weather, 
but  remain  friable  and  of  equal  bulk. 


CHAPTEE  ly. 

PHYSICAL  QUALITIES  OF  SOILS  AS  TO  HEAT  AND  WATER. 

^79.   Temperature  of  Soils. 

The  mean  annual  temperature  of  the  soil  is  about  that 
of  the  air.  During^  the  summer  it  is  warmer  durino-  the 
day  and  cooler  at  night.  At  a  depth  of  three  feet  from 
the  surface  it  is  unchanged  from  day  to  night,  and  seventy- 
five  feet  below  the  surface  the  thermometer  never  varies. 
In  tropical  regions  the  point  of  unvarying  temperature  is 
reached  about  one  foot  from  the  surface. 

There  are  two  sources  of  heat  to  the  soil :  one  external, 
from  the  solar  rays,  the  other  internal,  produced  by  the 
chemical  process  of  oxidation  or  decay.  The  warmth  of 
the  soil  which  favors  the  growth  of  plants  is  due  mainly, 
if  not  entirely,  to  the  sun.  The  earth  has  a  heat  within 
itself,  which  keeps  up  a  high  temperature  in  its  interior, 


112 


SOILS  AS  RELxiTED  TO  PHYSICS. 


bat  it  escapes  so  rapidly  from  its  surface  that  there  would 
be  eternal  winter  but  for  the  genial  sunshine. 

The  temperature  of  the  soil  is  affected  by  its  color.  A 
black  soil  absorbs  and  retains  more  heat  than  a  gray  or 
white  soil.  The  latter,  however,  radiates  the  solar  rays 
back  upon  the  growing  crops,  so  as  to  often  prove  disas- 
trous to  them,  producing  the  death  of  the  corn  tassels  and 
young  cotton  bolls. 

When  the  humus  is  exhausted  from  a  sandy  soil  by 
cultivation,  it  generally  assumes  a  whitish  color,  and  the 
only  way  to  restore  it  is  by  resting  for  a  number  of  years 
until  it  becomes  dark  again  from  the  vegetable  mould. 
Experiments  have  been  made  by  Lampodius  and  others, 
by  which  good  crops  were  made  on  a  white  soil  by  the 
application  of  charcoal  over  the  surface. 

Prof.  Johnson,  on  a  July  day  at  noon,  tested  the  tem- 
perature of  the  soil,  the  air  being  90^.  A  thermometer 
placed  at  the  depth  of  one  inch  below  the  surface,  gave 
the  following  results : 


The  angle  at  which  the  sun  strikes  a  soil  has  great 
influence  upon  its  temperature,  as  has  been  observed  in 
cold  climates.  A  difference  of  8^  has  been  noted  between 
hillsides  with  a  southern  exposure,  and  level  lands  which 
receive  the  rays  of  the  sun  obliquely.  Such  soils,  all  other 
things  being  equal,  might  be  planted  much  earlier,  and 
would  be  more  productive. 

Schubler  made  experiments  with  a  number  of  soils  as 
to  the  effect  of  color  and  moisture  upon  their  temperature. 


Quartz  sand  

Crystalline  lime  soil 

Garden  soil  , 

Yellow  sand-clay. . . 

Pipe-clay   

Chalk  soil  , 


,126^ 

115 

114 

100 

.94 

.87 


RETENTIVE  POWER  OF  SOIL  FOK  HEAT. 


113 


The  average  temperature  of  soils  whitened  by  magnesia 
was  108.5.    Of  those  blackened  by  lampblack  121.4. 

Wet.  Dry. 

Gray  plough  land  97.7^  111.7^ 

Heavy  clay  soil,  yellowish  gray  99.3   112.3 

Garden  mould,  blackish  gray  99.5   113.5 

Humus,  brownish  bJ ack  103.6  1 17. 3 

80.    Capacity  of  the  Soil  for  Heat. 

M.  Becquerel  has  made  some  interesting  experiments 
in  reference  to  the  capacity  of  different  kinds  of  soil  for 
heat.  That  is,  the  same  degree  of  heat,  natural  or  artificial, 
that  would  bring  a  calcareous  sand  to  100^  would  bring  a 
silicious  sand  to  95.6,  etc. 

The  following  will  show  the  capacity  of  several  different 
soils  for  heat: 


Calcareous  sand  100.0 

Silicious  sand  95.6 

Argillaceous  earth   68.4 

Calcareous  earth  61.8 

Mould  49.0 


Thus  a  sandy  soil  is  warmer  than  a  clay  soil,  while 
a  vegetable  mould  has  less  capacity  for  heat  than  any 
other  earth.  In  a  warm  climate,  tlien,  humus  is  a  refri- 
gerator of  the  soil,  which  renders  it  useful  in  hot,  dry 
weather.  In  more  northerly  latitudes,  this  might  be  a 
disadvantage,  as  they  require  heat  rather  than  moisture. 

81.  Retentive  Power  of  Soils  for  Heat, 

As  a  general  rule,  the  larger  and  denser  the  particles 
of  a  soil,  the  slower  it  parts  with  its  heat.  Thus  a  soil 
covered  with  gravel  cools  much  more  slowly  than  a  fine 
sand.  This  is  the  prime  reason  why  such  soils  are  so  well 
adapted  to  grapes  in  a  cold  climate.    They  have  but  small 


114 


SOILS  AS  RELATED  TO  PHYSICS. 


deposits  of  dew  on  tlieir  surface,  owing  to  their  slowness 
in  radiating  heat. 

M.  Becquerel  tested  this  quality  in  several  different 
classes  of  soils,  as  follows.  He  took  a  cube  of  18  solid  feet 
of  each  different  kind  of  soil,  and  heated  it  up  to  144^, 
noting  the  time  it  took  to  be  reduced  to  70^,  the  surround- 
ing air  being  61*^.    Result : 


Hours.  Min. 


Mould  

 1.... 

Thus  a  vegetable  loam  will  radiate  heat  at  the  close  of 
a  hot  summer  day,  twice  as  fast  as  a  sandy  soil,  inducing 
a  much  greater  deposition  of  dew,  which  in  the  dry,  hot 
days  of  summer  must  be  very  advantageous  to  growing 
crops.  And  when  it  is  remembered  that  the  interspaces 
of  the  soil  for  12  inches  or  more  are  filled  with  air  contain- 
ing more  or  less  vapor  which  deposits  moisture  in  the  same 
way,  the  value  of  mould  in  time  of  drought  cannot  well  be 
estimated. 

These  conditions  apply  especially  to  the  leading  crops 
of  the  South,  corn  and  cotton,  which  leave  the  soil,  when 
properly  cultivated,  comparatively  naked.  Soils  covered 
with  vegetation,  as  by  clover  and  the  grasses,  are  not  so 
much  concerned  in  these  processes,  as  their  temperature  is 
much  more  uniform. 

82.  Permeability  to  Water  in  Soils. 

One  of  the  most  important  physical  qualities  of  a  soil 
IS  its  permecihility  to  water^hj  ^\\\\Q\\  the  two  great  func- 
tions of  imbibition  and  capillary  power  are  manifested. 
A  soil  may  have  all  other  physical  qualities  as  well  as 
chemical,  its  salts  being  abundant  and  in  soluble  forms,  and 


PER^IEABILITY  TO  AVATER  SOILS. 


115 


yet,  deprived  of  this,  obstruction  and  death  would  ensue  to 
the  plant;  indeed,  germination  could  never  take  place. 

The  degree  of  permeability  of  a  soil  depends  upon  the 
size  of  its  pores.  Coarse  gravelly  soils  have  but  few  pores, 
but  they  are  very  large,  and  water  percolates  through 
them.  This  is  a  disadvantage,  as  soluble  matters  are  thus 
carried  off  too  rapidly.  Soils  composed  of  finer  particles 
of  clay,  sand,  and  organic  matter,  have  many  minute  pores, 
which  let  the  water  in  slowly,  and  hold  it  to  saturation. 
These  soils  have  great  capillary  power  or  surface  attrac- 
tion. 

This  peculiar  force  may  be  illustrated  by  a  small  vial 
partly  filled  with  water.  The  liquid  will  adhere  to  its 
sides  and  the  water  present  a  concave  surface.  In  a  very 
narrow  tube,  the  water  will  rise  to  a  considerable  height; 
the  surface  attraction  overcoming  the  power  of  gravitation. 
On  this  principle  water  rises  in  the  pores  of  a  sponge,  or  in 
a  lump  of  sugar  or  salt. 

Where  a  soil  is  so  compact  (as  in  some  clays)  as  to  run 
together  and  become  cemented,  not  only  does  a  great  dis- 
advantage accrue  by  its  loss  of  power  to  absorb  water, 
but  also  the  air  is  precluded  to  a  large  extent;  and  plants 
do  not  germinate  well  in  such  soils,  owing  to  a  lack  of  free 
oxygen. 

In  1873  we  experimented  in  two  barrels,  one  a  surface 
soil  having  organic  matter  and  being  porous,  the  other  a 
subsoil  with  but  little  organic  matter.  The  cotton  seed  in 
the  former  came  up  and  the  plant  grew  finely.  In  the 
other,  not  a  seed  germinated  until  the  third  planting;  for 
in  applying  the  water  to  give  the  soil  moisture,  it  would 
become  so  cemented  as  to  prevent  the  free  access  of  air 
even ;  and  to  this  physical  defect  we  attribute  more  the 
non-fertility  of  the  soil,  than  to  any  deficiency  in  nutritive 
matters. 

The  diffusibility  of  water  in  a  soil  depends  upon  its 


116 


SOILS  AS  RELATED  TO  PHYSICS. 


capillary  and  imbibing  powers  to  a  great  extent.  A  good 
illustration  is  the  burning  of  a  lampwick  saturated  with 
oil.  As  the  oil  is  consumed  in  the  upper  portion  of  the 
wick  it  is  supplied  from  below  by  capillary  attraction. 
So  when  the  surface  of  a  soil  is  rendered  dry  by  the  sun's 
rays  and  the  winds,  the  moisture  rises  from  the  subsoil 
and  supplies  to  a  large  extent  the  evaporated  moisture. 

Thus,  during  the  intense  droughts  of  summer,  some 
soils  well  adapted  by  the  size  of  their  pores  to  capillary 
force,  are  constantly  receiving  supplies  of  moisture  from 
below,  while  on  others  the  crops  soon  wither  up  and  die 
for  the  lack  of  this  power. 

And  thus  nature  furnishes  supplies  of  water  in  the 
heavy  rains  of  winter,  by  saturating  the  subsoil,  to  fur- 
nish through  this  beneficent  power  a  supply  when  the 
clouds  refuse  them  in  the  heat  of  summer.  When  the 
surface  soil  becomes  more  moist  than  the  subsoil,  as  after 
rain,  the  capillary  force  ceases  to  bring  the  water  up, 
and  rather  aids  gravity  to  carry  it  downward  in  the  soil. 

In  regions  like  California,  where  rains  fall  period- 
ically, the  rising  of  water  to  the  surface  during  the  long- 
dry  season  causes  soluble  salts  to  come  up  with  the  water, 
and  thas  incrustations  are  formed  on  the  surface,  to  be 
dissolved  and  carried  down  again  by  the  first  rain.  Soils 
in  Bengal  thus  saturated  with  nitre  during  the  dry  season, 
produce  luxuriant  crops  when  the  I'ain  sets  in. 

The  immense  beds  of  carbonate  of  soda  and  other 
salts  in  the  deserts  of  Utah,  and  the  nitrate  of  soda-beds 
in  Peru,  are  supposed  to  have  originated  thus.  This 
latter  salt  is  brought  from  its  deposits  and  used  exten- 
sively in  this  country  and  Europe  to  mix  with  fertilizing 
compounds. 

Thus  water  charged  with  carbonic  acid  and  oxygen 
is  constantly  circulating  up  and  down  through  the  soil, 
acting  upon  the  silica,  lime,  phosphoric  acid,  and  potash, 


HYGROSCOPIC  POWER  FOR  WATER. 


Ill 


rendering  them  soluble,  and  supplying  them  directly  to 
the  feeders  of  the  plants. 

83.  Hygroscopic  Power  for  Water, 

The  liygroscopic  or  absorptive  power  of  soils  is  an- 
other and  very  essential  quality.  This  is  the  power  to 
imbibe  vapor  from  the  air  and  condense  it  in  its  pores. 

There  can  be  no  upward  movement  of  water  in  the 
soil  without  evaporation.  The  absorbing  power  of  soils 
for  the  watery  vapor  of  the  atmosphere  opposes  evapora- 
tion ;  hence  this  process  is  influenced  not  only  by  the  sun 
and  winds,  but  also  by  the  soil.  Liquid  water  is  also  im- 
bibed and  held  by  some  soils  more  tenaciously  than  others. 

In  the  following  table,  from  experiments  by  Schubler, 
the  first  column  shows  the  percentage  of  liquid  water 
absorbed  by  a  dry  soil,  and  the  second  the  amount  of 
water  that  evaporated  from  them  in  four  hours  after  com- 
plete saturation. 

Quartz  sand  25  88.4 

Clay  soil  (60  per  cent,  clay)  40  52.0 

Loam  51  45.7 

Plough  land  52  32.0 

Heavy  clay  (80  per  cent,  clay)  61  34.9 

Garden  mould  89  24.3 

Humus  181  25.5 

Thus  we  perceive  that  the  soil  which  imbibes  the 
most  water  holds  it  most  tenaciously,  and  vice  versa. 
Contrast  quartz  sand  and  garden  mould.  One  absorbs 
just  as  much  as  the  other  lets  off  in  both  instances.  Soils 
which  have  this  imbibing  and  retaining  power  for  water 
are,  other  things  being  equal,  much  the  best  for  a  warm 
climate. 

It  will  thus  be  perceived  that  the  power  of  a  soil  to 
imbibe  water  depends  greatly  on  its  percentage  of  clay, 
and  that  this  power  is  greatly  increased  by  the  addition 
of  humus.    Sandy  soils  are  in  themselves  dry  and  arid. 


118 


SOILS  AS  RELATED  TO  PHYSICS. 


and  it  is  of  the  utmost  importance  for  such  soils  to  be 
furnished  with  organic  matter. 

The  rapidity  of  absorption  is  always  increased  when 
the  air  is  moist.  Knop  has  shown  that  the  amount  is 
always  determined  by  the  temperature,  i.  e.  at  a  given  tem- 
perature, the  same  quantity  of  moisture  will  be  absorbed 
by  a  dry  soil,  but  it  will  take  longer  to  do  it. 

A  soil  possessing  this  hygroscopic  power  may  be 
greatly  benefited  in  time  of  drought,  by  imbibing  during 
the  cool  night-time  much  of  the  moisture  lost  in  the  hot 
day,  and  imparting  thereby  nutriment  and  strength  to 
perishing  plants. 

From  experiments  made  by  Sir  H.  Davy,  on  a  number 
of  soils  of  different  degrees  of  productiveness,  he  found 
that  the  most  fertile  soils  always  possessed  these  qualities 
in  a  higher  degree  than  the  less  fertile. 

Zenger  made  experiments  on  soils  as  to  the  effect  of 
their  state  of  division  on  their  power  of  imbibing  water. 
He  proved  that  porous  soils  w^ould  lose  this  power  in  the 
ratio  of  their  being  made  fine;  while  those  more  cemented 
in  structure  would  acquire  greater  powers  of  absorption. 
In  the  following  table,  the  imbibing  power  of  each  soil 
is  presented  in  the  two  classes  of  soils,  one  of  equal 
coarseness,  and  the  other  reduced  to  extreme  fineness  by 
pulverization. 

Coarse,  Fine. 

Quartz  sand  28.0  53.5 

Marl  30.2  54.5 

Brick  clay  66.2  57.5 

Moor  soil  104.5  101.0 

Aim  soil  178.2  102.5 

Peat  dust  377.0  268.5 

84.  Hetentive  Poiver  for  Water. 

The  power  of  retaining  or  holding  water  in  its  pores 
is  another  quality  to  be  considered.    Water  poured  upon 


EETEXTIVE  POWEK  FOR  WATER. 


119 


a  lump  of  pipe-clay  or  other  soil  drop  by  drop,  will  ulti- 
mately saturate  it  so  it  can  hold  no  more. 

Experiments  made  by  Schubler  established  the  follow- 
ing facts  :  That  106  pounds  of  different  kinds  of  soils  will 
absorb  the  number  of  pounds  of  water  stated  as  follows: 


Calcareous  sand  29  lbs. 

Loamy  soil  40  '* 

English  chalk  45  " 

Clay  loam  30  " 

Pure  clay  TO 


While  this  is  a  valuable  quality  in  warm  climates,  in 
keeping  up  moisture  and  reducing  the  temperature  of  a 
soil,  it  might  prove  disadvantageous  in  a  northern  climate, 
where  they  have  to  husband  warmth  and  sunshine,  rather 
than  moisture  and  a  reduced  temperature. 

A  porous  soil,  with  tubes  sufficiently  large  to  suck  up 
the  water  like  a  sponge,  upon  the  principle  of  capillary 
attraction,  possesses  the  power  of  holding  water  more  than 
other  soils:  too  much  porosity  will,  however,  act  reversely. 
Some  soils  have  such  small  apertures  as  to  prevent  the 
access  of  water  to  such  an  extent,  as  to  render  them  unfit 
for  cultivation. 

Another  advantage  of  soils  which  retain  water,  is  that 
they  hold  soluble  matters,  applied  as  fertilizers,  or  natu- 
rally produced,  for  the  benefit  of  plants. 

Good  arable  soils  are  able  to  hold  from  40  to  70  per 
cent,  of  their  weight  of  water.  Under  40  per  cent,  reduces 
them  below  the  point  of  remuneration,  while  above  70 
makes  them  cold  and  unproductive.  Farmers  learn  by 
experience  places  in  their  fields  which  dry  soonest  after 
rain,  as  they  can  always  plough  them  first  ;  they  also  suf- 
fer earliest  from  dry  weather.  These  soils  are  always 
deficient  in  clay  and  humus. 

Soils  possessed  of  a  medium  retentive  power  are  the 


120 


SOILS  AS  RELATED  TO  PHYSICS. 


most  fertile.  While  those  which  are  deficient  in  this  im- 
portant quality  are  unfruitful  to  the  degree  of  the  defi- 
ciency. Those  possessing  too  much,  as  some  clay  soils, 
will,  especially  after  heavy  rains,  and  in  temperate  lati- 
tudes, produce  a  coldness  adverse  to  fruitfulness. 


CHAPTEE  V. 

"WATER  AS  A  PHYSICAL  AGENT  IN  THE  SOIL, 

85.  Its  Modes  of  Existence, 

Water  has  much  to  do  with  the  physical  character  of 
the  soil.  It  has  been  noticed  as  existing  under  three  con- 
ditions, viz.  hydrostatic^  capillary^  and  hygroscopic. 

Water  also  exists  in  the  soil  chemically  combined,  as  in 
zeolites,  kaolin  (true  clay),  the  oxides  of  iron,  quartz,  etc. 
As  this  w^ater  requires  a  very  high  heat  to  ex]Del  it  from 
its  combinations,  it  can  never  be  of  any  service  to  plants, 
or  have  any  special  influence  on  the  soil  itself,  only  so  far 
as  it  is  connected  with  the  substances  in  which  it  exists. 

86.  Of  Hydrostatic  Water, 

Hydrostatic  loater  relates  to  that  which  flows  through 
the  soil,  may  be  seen  by  the  eye,  and  is  free  to  move  about 
by  the  laws  of  gravity  or  any  other  force.  This  is  always 
more  abundant  after  rains,  melting  of  snows,  etc.  The 
pores  of  the  soil  at  these  times  become  surcharged  with 
this  hydrostatic  water,  until  it  is  carried  off  by  evaporation 
or  sinks  down  into  lower  situations  to  unite  with  drains 
and  currents  many  feet  below  the  surface. 

This  is  called  bottom  loater^  which  rises  and  falls  with 
wet  and  dry  seasons.  After  long-continued  rains,  and 
especially  in  low  situations,  this  bottom  water  ajDpears  neai 


HYGROSCOPIC  WATER. 


121 


the  surface  and  acts  very  disastrously,  by  submerging  the 
roots  of  the  growing  crops.  This  frequently  results  in  level 
lands  during  wet  springs,  to  the  serious  detriment  of  crops. 
In  table-lands  such  a  condition  is  not  to  be  apprehended, 
only  in  valleys  and  low  places. 

When  this  bottom  water  is  but  a  few  inches  from  the 
earth's  surface,  we  have  bogs  and  swamps,  not  fit  for  any- 
thing but  water  plants,  such  as  reeds  and  rushes.  When 
it  exists  from  two  to  three  feet  from  the  surface,  and  the 
soil  is  of  an  open  texture,  the  grasses  and  some  other  plants 
will  grow  well  u^on  it.  When  it  is  not  more  than  six  or 
eight  feet,  and  the  soil  light  and  loamy,  it  is  favorable  for 
all  classes  of  vegetable  growth,  on  account  of  the  constant 
supply  of  water  afibrded  the  roots  by  capillary  attraction, 
especially  in  dry  seasons. 

87.    Capillary  Water, 

Cajnllary  water  is  properly  the  moisture  in  a  soil,  which 
cannot  be  seen  by  the  naked  eye  as  water,  yet  when  exist- 
ing to  any  great  extent  is  easily  discernible  as  a  moist  or 
wet  soil. 

Being  no  longer  subject  to  hydrostatic  law,  capillary 
water  is  held  by  this  peculiar  force,  adhering  with  consid- 
erable tenacity  to  the  particles  of  earth. 

When  a  soil  saturated  with  water  is  air-dried,  the 
escaping  moisture  is  properly  what  is  termed  capillary; 
although  it  is  difficult  to  draw  a  distinct  line  between 
that  and  hygroscopic  water. 

As  a  general  rule,  the  finer  the  pores  of  a  soil,  the 
greater  its  capillary  power.  It  exists  in  greater  or  less 
abundance  for  some  distance  above  the  line  of  bottom 
water,  according  to  the  size  of  the  pores  in  the  soil. 

88.  Hygroscopic  Water. 

Hygroscopic  loater  is  closely  blended  with  the  particles 
6 


122 


SOILS  AS  RELATED  TO  PHYSICS. 


of  the  soil ;  so  much  so  that  the  eye  cannot  detect  its  pre- 
sence. It  is  only  ascertained  by  the  loss  or  increase  of 
organic  weight,  as  the  soil  is  deprived  of  it,  or  acquires  it. 
When  a  soil  is  air-dried  it  loses  all  of  its  capillary  water. 
One  hundred  grains  of  this  kept  at  about  the  boiling  point 
for  several  hours  will  lose  its  hygroscopic  water. 

The  amount  of  this  water  in  the  soil  is  very  variable, 
being  reduced  as  low  as  -J  per  cent,  in  dry  weather,  and 
rising  to  40  per  cent,  after  rain,  in  some  soils.  It  increases 
during  the  night,  being  imbibed  from  the  atmosphere  or 
deposited  as  dew,  and  diminishes  during  the  day  by  evapo- 
ration. 

The  distinctions  between  hydrostatic,  hygroscopic,  and 
capillary  water,  are  not  absolute  in  their  character,  but 
simply  relate  to  the  degree  in  which  the  water  exists  in 
the  soil,  and  serves  a  good  purpose  in  this  way.  There 
can  be  no  precise  boundary  l^etween  hydrostatic  and  capil- 
lary water,  for  instance,  especially  where  the  soil  has 
minute  pores. 

89.  Supply  of  Water  to  Plants, 

Hydrostatic  water  rarely  serves  as  nourishment  for 
plants,  but  on  the  contrary  olFers  obstructions  to  their  pro- 
per nutrition.  In  rare  cases,  however,  some  plants  send 
out  their  roots  in  fountains  and  drains  for  food. 

As  a  general  rule,  agricultural  plants  get  their  nourish- 
ment from  the  soluble  matters  of  capillary  and  hygroscopic 
water.  And  as  plants  are  known  to  exhale  large  quan- 
tities of  water  from  their  leaves,  and  even  their  roots,  the 
amount  of  water  thus  taken  up  by  the  fibrils  must  be  in 
correspondence  with  the  amount  exhaled. 

The  healthiness  of  plants  and  their  very  existence  de- 
pend on  a  proper  supply  of  water,  surcharged  with  nutri- 
tive substances ;  as  their  food  must  be  held  in  solution  by 
it  and  can  only  penetrate  their  cells  and  tissues  through 


HOW  PLANTS  ABSORB  WATER. 


123 


this  as  a  menstruum.  Other  solvents,  as  carbonic  acid  and 
ammonia,  have  to  be  diluted  with  water  before  the  sub- 
stances dissolved  by  them  can  be  appropriated  as  plant- 
food. 

Sachs  proved,  in  an  experiment  with  a  young  bean  j^lant, 
that  the  water  exhaled  from  its  leaves  was  sui^plied  by  the 
hygroscopic  moisture  of  a  soil,  which  it  absorbed  from  the 
damp  air  surrounding  it.  The  foliage  of  the  plant  was 
allowed  free  access  to  fresh  dry  air,  while  the  pot  of  soil 
containing  the  roots  was  confined  in  an  atmosphere  satu- 
rated with  vapor  of  water. 

He  also  showed,  in  other  experiments,  that  roots  not  in 
contact  with  the  soil  lose  water  continually,  and  cannot 
obtain  it  from  damp  air  ;  thereby  demonstrating  that  soils 
(especially  clay  and  humus)  condense  vapor  in  their  pores, 
holding  it  as  hygroscopic  water  for  the  benefit  of  plants. 

Then,  the  soil  is  the  medium  through  which  plants 
receive  their  water,  nor  can  the  roots,  much  less  the  leaves, 
obtain  it  in  appreciable  quantities  from  the  atmosphere. 

When  a  plant  begins  to  wilt,  it  is  evident  that  the  soil 
is  exhausted  of  the  water  which  it  can  absorb  from  it. 
Sachs  took  advantage  of  this  fact,  and  found  in  one  soil, 
that  it  held  8  per  cent,  of  water,  unapjDropriated  by  a  to- 
bacco plant.  This  soil  was  capable  of  absorbing  52.1  per 
cent,  of  water.  Thus  it  had  the  power  of  furnishing  44.1  per 
cent,  of  its  weight  of  water  to  plants.  A  coarse  sand  was 
found  to  absorb  20.8  per  cent,  of  watei*,  and  yield  all  but  1.5 
per  cent,  to  a  tobacco  plant.  A  mixture  of  humus  and  sand 
held  46  per  cent,  of  capillary  water,  and  furnished  all  but 
12.3  per  cent,  to  the  plant  before  wilting. 

90.  Hoio  Plants  absorb  Water. 

An  interesting  question  is.  How  do  plants  take  up 
water  from  the  soil?  Dead  plants  retain  much  water,  and 
after  being  dried,  are  capable  of  absorbing  a  portion  of  it 


124 


SOILS  AS  RELATED  TO  PHYSICS. 


again.  Wheat  straw  and  corn  stalks,  when  thoroughly  air- 
dried,  retain  12  to  15  per  cent,  of  water,  and  absorb  much 
more  in  a  moist  atmosphere. 

One  hundred  parts  of  the  following  substances  (experi- 
ments by  Trommer),  when  dry,  absorbed  from  a  damp  at- 
mosphere, as  follows  : 

12  hours.    24  hours.    48  hours.    72  hours. 

Barley  straw  15  24  34  42  parts  of  water. 

Rye        "   12  20  27  29  " 

White  paper  8  12  17  19  " 

The  term  hygroscopic  implies  an  attraction  for  water. 
This  attractio7i  is  called  adhesion,  or  adhesive  attraction. 
A  law  of  attraction  is  that  distance  weakens  its  force.  It 
only  acts  intensely  then  at  small  distances.  A  lump  of  dr}^ 
clay  will  absorb  water  rapidly  by  its  external  pores  ;  more 
feebly  and  slowly  nearer  the  centre,  until  it  ceases  entirely 
at  a  certain  distance  from  the  surface. 

Two  hygroscopic  bodies,  one  dry,  the  other  saturated 
with  water,  placed  in  contact,  would  form  an  equilibrium 
as  to  the  amount  of  water  on  their  surfaces  at  least,  the  dry 
absorbing  from  the  moist ;  on  the  same  principle,  the  active 
roots  of  plants  would  easily  take  up  water  from  a  moist 
soil  in  contact  with  them.  As  water  evaporates  from  the 
leaves,  or  is  decomposed  within  the  plant  and  appropriated, 
the  vacuum  produced  absorbs  water  from  the  adjacent 
tubes  below,  and  thus  a  constant  current  is  established 
down  to  the  extremities  of  the  roots,  which  in  their  turn 
(being  eminently  hygroscopic)  suck  up  water  from  a  com- 
paratively dry  soil.  (Johnson.) 

The  supply  and  waste  of  water  to  a  plant  may  be  une- 
qual to  a  certain  extent,  without  detriment  ;  but  when  the 
exhalation  is  more  rapid  than  the  supply  for  a  length  of 
time,  owing  to  a  dry  soil,  the  plant  wilts  and  becomes  un- 
healthy, although  it  may  possess  a  larger  percentage  of 


HOW  PLANTS  ABSORB  WATER. 


125 


water  than  the  soil.  Some  plants  contain  80  per  cent,  of 
water,  while  soils  hold,  according  to  Sachs,  from  1.5  to  12.3 
per  cent,  of  water.  Vegetable  matter,  fully  air-dried,  will 
hold  from  13  to  15  per  cent.  Average  soils  do  not  retain 
more  than  2  or  3  per  cent.  This  shows  conclusively  that 
])lants  are  much  more  hygroscopic  than  soils. 

From  experiments  made  by  Sachs,  it  is  admitted  that 
the  foliage  as  well  as  stems  and  roots  of  plants  absorb,  to 
a  small  extent,  water  from  the  atmosphere,  but  the  absorp- 
tion of  liquid  water  from  the  soil  proceeds  at  least  one 
thousand  times  more  rapidly  than  from  the  air,  which  may 
be  considered  as  the  only  real  source  of  supply. 

The  amount  of  root  surface  to  that  of  the  soil  in  which 
a  plant  grows  is  very  small.  Boussingault  found  that  a 
dwarf  bean  spread  its  roots  in  51  pounds  of  soil ;  a  potato 
plant  in  190  pounds  ;  a  tobacco  plant  470  pounds,  and 
a  hop  plant  2,900  pounds,  equal  to  50  cubic  feet.  This 
shows  that  even  if  roots  did  not  possess  a  greater  power 
of  absorption  than  water,  they  possess  much  greater  capa- 
city for  its  imbibition. 

The  quantity  of  water  in  vegetation  is  always  influ- 
enced by  the  amount  in  the  soil.  Thus  De  Saussure  found 
that  plants  growing  in  a  moist  loam  contained  more  water 
than  those  in  a  dry  lime  soil.  So,  of  a  wet  summer,  grass 
and  weeds  are  more  succulent,  and  the  green  crop  heavier 
than  of  a  dry  summer.  The  hay,  however,  when  dried,  loses 
so  much  more  water,  that  the  amount  may  be  nearly  the 
same. 

Ritthausen,  in  1854,  gave  the  produce  of  two  crops  of 
clover  from  a  loamy  soil,  as  follows : 

WEIGHT  m  POUNDS  PER  ACRE. 

Fresh.  Air-dry.    Water  lost  in  drying. 

1.  Manured  with  ashes  14.903  5.182   9.721 

Unmanured  12.380  5.418   6.962 

2.  Manured  with  gypsum.. .  .22.256  4.800.  17.456 

Unmanured  18.815  5 . 190  13 . 625 


126 


SOILS  AS  RELATED  TO  PHYSICS. 


It  is  a  singular  fact  that  tlie  immanured  plots  produced 
more  hay  than  those  manured,  notwithstanding  the  bulk 
was  much  in  favor  of  the  latter.  The  water  constituted  the 
dilierence.  The  stems  of  the  unmanured  clover  were  much 
more  compact  than  the  other. 

91.  liequisite  Amoimt  of  Water  in  Soils  for  Plants, 

The  quantity  of  water  supplied  to  a  soil  has,  as  we  all 
know,  much  to  do  with  its  production.  A  dry  year  always 
cuts  off  the  crop  of  corn  and  cotton,  w^hile  too  much  rain 
is  equally  injurious,  especially  to  cotton. 

Ikenhoff  made  experiments  on  buckwheat  as  to  the 
amount  of  water  requisite  for  a  maximum  crop.  He  filled 
pots  with  garden  earth,  of  the  same  size,  and  placed  them 
in  a  southern  exposure.  The  plants  in  pot  No.  1  received 
^  litre  of  water  each  time,  being  a  little  less  than  an  Eng- 
lish pint.  No.  2,  ^  litre  ;  No.  3,  \  litre  ;  No.  4,  and  No. 
5,  litre.  The  plants  were  watered  17  times  in  67  days. 
The  following  shows  the  product  of  each  pot  : 


Straw. 

Water  used, 
in  litres. 

No.  1. 

Ill  seeds,  weighing  1.68  grammes. . 

..4.52... 

 25.0 

No.  2. 

282         "  5.47 

..8.47... 

 12.5 

No.  3. 

93         "  1.73 

..4.55... 

  6.25 

No.  4. 

37         "  0.52 

..0.30... 

 3.12 

No.  5. 

12         "             0.09  . 

..0.30... 

  1.56 

This  experiment  teaches  that  the  amount  of  water  in  a 
soil  has  much  to  do  with  the  production  of  plants.  It 
should  not,  however,  be  taken  as  a  rule  for  all  soils.  In 
fact  no  general  rule  can  be  given  as  to  how  much  is  requi- 
site, some  soils,  as  some  crops,  demanding  more  than 
others. 

Hellriegel  experimented  with  wheat,  rye,  and  oats  in 
sand  mixed  wdth  a  sufficiency  of  plant-food  furnishing  from 
2^  to  20  per  cent,  of  water:  10  to  15  per  cent,  of  water 


REQUISITE  AMOUNT  OF  WATER  FOR  PLANTS. 


127 


produced  n  maximum  crop  of  rye — wheat  and  oats  requir- 
ing a  little  more.  Wilting  never  took  place  except  when 
the  percentage  of  water  was  reduced  below  2^.  Above  this 
the  growth  was  stunted  more  or  less  up  to  10  per  cent. 

Groven  found  in  fourteen  experiments  in  the  open  field, 
in  various  parts  of  Germany  and  Austria,  on  sugar  beets, 
that  the  eight  best  crops  received,  from  the  time  of  plant- 
ing to  gathering,  140  Paris  lines  of  water  in  depth  ;  the  six 
poorest  115  lines,  equal  to  about  37  inches. 

There  is  no  fact  better  established  than  that  water  is 
the  most  essential  factor  in  the  production  of  a  crop. 
Perhaps  temperature  is  equally  so,  as  nothing  can  vege- 
tate without  proper  warmth.  An  abundant  supply  of 
water,  when  needed,  will  produce  good  crops  even  on 
poor  soils,  while  the  richest  will  utterly  fail  without  it. 

The  physical  offices  of  water  are  very  important.  All 
the  nutritive  matters  that  circulate  in  the  plant  are  held 
in  solution  by  this  agent,  and  carried  forward  to  its  extreme 
parts.  Not  only  are  the  solid  matters  brought  up  through 
the  roots  thus  distributed,  but  the  gases  imbibed  by  the 
leaves  also  impregnate  the  sap,  and  are  carried  and  depo- 
sited wherever  needed.  The  very  force  of  absorption  has 
a  tendency  to  enlarge  the  cells  and  expand  the  tubes,  and 
thus  add  to  the  growth  of  the  plant,  while  a  deficiency  of 
this  vital  fluid  will  produce  smaller  cells  and  a  stunted 
growth. 

The  solid  matters  of  the  soil  are  also  dissolved  by 
water,  especially  when  surcharged  with  carbonic  acid  and 
ammonia,  and  doubtless  through  this  agency,  chemical 
actions  are  constantly  going  on  in  the  soil,  by  the  moving 
of  hygroscopic  and  capillary  waters  through  the  solid 
strata  of  insoluble  matter. 


128 


SOILS  AS  RELATED  TO  PHYSICS. 


CHAPTER  VL 

MECHANICAL  IMPROVEMENT  OF  SOILS. 

92.    Of  Drainage, 

Among  the  mechanical  means  for  the  improvement  of 
the  soil,  so  important  in  older  countries,  drainage  stands 
preeminent.  This  process  is  practised  at  the  North  and 
in  Europe  very  extensively,  even  on  uplands.  This  is 
done  in  order  to  get  clear  of  the  moisture  as  much  as  possi- 
ble, and  thereby  make  the  land  warmer  and  hasten  the 
growth  of  crops;  for  it  is  known  that  too  much  water 
makes  land  cold  and  retards  vegetation. 

This  system  of  drainage  is  the  very  thing  for  cold 
countries,  as  it  improves  the  climate,  so  to  speak,  by 
relieving  the  soil  of  the  chilly  moisture  and  letting  in  the 
genial  sunshine.  It  acts  also  unquestionably  very  favor 
ably  in  aiding  the  decomposition  of  insoluble  substances, 
both  of  organic  and  inorganic  matters  of  the  soil. 

Air  is  indispensable  to  the  soil  to  prepare  food  for  plants 
by  the  chemical  action  of  oxygen  and  carbonic  acid  ;  as 
well,  it  may  be,  to  supply  nitrogen  to  the  interspaces  of 
the  soil,  by  which  it  may  be  charged  and  made  soluble 
food  for  plants.  A  soil,  then,  in  a  healthy  condition,  is 
full  of  pores  and  crevices  by  which  the  air  is  let  into  it, 
and  the  gases  escaping  from  decomposing  organic  sub- 
stances may  circulate  in  it  and  act  chemically  upon  its 
insoluble  substances.  But  when  bottom  water  rises  in  the 
soil  it  prevents  the  access  of  air,  as  well  as  the  capillary 
water,  to  a  large  extent,  from  rising  in  the  surface  soil, 
when  but  a  few  feet  intervene. 

In  stagnant  waters  many  compounds  are  formed  inju- 
rious to  vegetation  as  well  as  to  the  health  of  man.  When 


OF  DRAINAGE. 


129 


a  shower  of  rain  falls  on  a  porous  soil  the  water  presses 
the  air  through  to  lower  depths,  which  is  followed  by  a 
fresh  supply  from  the  atmosjDhere,  and  thus  chemical  action 
is  readily  carried  on  :  the  ammonia  and  carbonic  acid  of 
the  rain  water  are  thus  secured  to  plants.  But  in  compact 
soils  not  properly  underdrained,  the  particles  run  together 
by  the  influence  of  rain,  and  the  water  runs  off  the  surface, 
or  is  carried  off  by  evaporation  ;  it  becomes  also  impervi- 
ous to  air.  Hence  the  valuable  constituents  of  rain  water 
as  well  as  of  the  atmosphere  are  lost  to  the  soil. 

All  soils  saturated  with  water  are  necessarily  cold. 
Steam,  whether  natural  or  artificial,  always  contains  a 
large  quantity  of  heat;  hence  the  evaporation  of  water, 
which  process  is  carried  on  by  the  conversion  of  it  into 
steam  or  vapor,  always  produces  heat.  Hence  the  heat 
produced  by  the  solar  rays  on  wet  ground,  is  lost  to  the 
soil  by  being  absorbed  by  the  vapor  which  is  constantly 
passing  off  from  such  a  soil  in  dry,  sunshiny,  or  windy 
weather. 

Miasma  is  also  generated  in  the  steam  of  stagnant 
waters,  where  drainage  is  neglected,  producing  malarial 
fevers.  If  you  mix  earth  and  water  in  an  open  vessel,  and 
let  it  stand  several  weeks  in  warm  weather,  an  offensive 
effluvia  will  arise,  clearly  proving  the  injurious  effects  of 
stagnant  water  upon  animals  as  well  as  plants. 

Thus,  by  draining,  the  soil  is  made  more  porous  and 
productive,  and  a  greater  depth  obtained  for  the  roots  of 
plants;  insuring,  also,  a  protection  from  drought,  especially 
over  the  underdrains,  and  for  some  distance  each  side,  by 
the  rise  of  capillary  water;  for  the  surface  attraction  of 
the  water  is  toward  the  ditches  as  well  as  to  the  surface, 
at  least  until  the  soil  in  them  becomes  as  compact  as  that 
between  them. 

Another  great  benefit  of  draining  is  the  rapidity  with 
which  the  soil  dries  off  after  rain;  thus  fitting  the  land  for 
6* 


130 


SOILS  AS  RELATED  TO  PHYSICS. 


ploughing  and  the  reception  of  seed  much  sooner  after 
long  spells  of  rainy  weather. 

It  often  happens  that  bottom  lands  are  wholly  lost  for 
a  whole  crop  by  continuous  spring  rains.  But  a  proper 
system  of  drainage  would  make  them  as  susceptible  of  cul- 
tivation as  most  uplands. 

Another  very  important  effect  of  draining  lands  inclined 
to  be  sobby  is,  that  fertilizers  will  act  much  better  in  a 
soil  moderately  dry  than  one  saturated  with  water.  Too 
much  water  in  a  soil  prevents  its  circulation,  and  thus  far 
deprives  roots  of  solvent  matters  held  by  water,  which  they 
would  otherwise  receive. 

The  moving  waters  of  a  soil  may  be  compared  to  a  bird 
feeding  her  young.  When  there  is  a  deposit  of  rich  food, 
the  roots  near  by  have  a  plenty,  but  those  below  are  suffer- 
ing, it  may  be,  until  a  shower  comes;  the  water  which 
passes  this  deposit  becomes  charged  with  soluble  matter, 
and  in  sinking  by  gravitation,  carries  down  to  the  lower 
roots,  especially  the  tap  roots,  as  of  cotton,  a  good  supply 
of  food.  As  soon  as  the  rain  is  over,  the  wind  and  sun- 
shine begin  to  dry  off  the  surface  soil  by  evaporation, 
Avhich  is  supplied  by  capillary  attraction  from  below,  and 
thus  from  the  same  rich  deposit,  which  the  hydrostatic 
water  carried  down  to  the  lower  roots,  the  capillary  water 
now  loads  itself  with  soluble  food,  and  brings  it  to  the 
upper  roots.  These  waters  also  supply,  to  a  considerable 
extent,  the  roots  laterally,  upon  the  principle  of  diffusibility 
already  noticed. 

The  free  circulation  of  the  air  through  the  soil  also 
aids  the  effects  of  fertilizers,  by  supplying,  when  needed, 
oxygen,  nitrogen,  and  carbonic  acid,  and  thus  forming  the 
exact  combinations  which  are  needed  by  plants.  Soils  too 
much  saturated  w^ith  water  will  prevent  this,  and  all  the 
advantages  growing  out  of  the  combinations  and  chemical 
changes  above  stated.    Thus  we  see  the  importance  of 


DEAmAGE  AT  THE  SOUTH. 


131 


artificial  drainage  in  all  soils  disposed  to  hold  too  much 
water, 

93.    Under  draining, 

Underdraining  is  a  work  requiring  much  practice  and 
skill,  and  if  not  done  well,  had  better  not  be  done  at  all. 
We  have  no  faith  in  any  of  the  processes  in  common  use 
among  farmers,  such  as  j)ine  logs,  stones,  brickbats,  etc. 
The  manufacture  of  tiles  for  this  purpose  is  much  better, 
and  any  farmer  having  a  bed  of  clay  on  his  land,  should 
establish  a  tile  factory,  and  make  and  burn  them  for  his 
own  use,  and  to  sell  to  others. 

Drain  tiles  are  made  in  various  forms:  the  two  mostly 
used,  and  the  best,  are  the  round,  and  the  half  circle,  or 
horse-shoe.  This  latter  is  in  two  parts,  one  long  and  flat, 
which  is  laid  on  the  bottom  of  the  ditch;  the  other,  a  half 
circle,  as  if  a  hollow  tube  had  been  split  in  two  from  end 
to  end.  This  lies  upon  the  flat  bottom  piece,  which  forms 
a  half  circle  for  the  water  to  pass  through.  The  round  tile 
is  much  the  most  convenient,  being  about  three  feet  in 
length,  larger  at  one  end  than  the  other,  which  acts  as 
a  sheath  for  the  small  end  of  its  fellow,  while  the  other 
end  penetrates  a  third,  thus  forming  a  continuous  tunnel 
through  the  ditch.  The  water  percolates  into  the  joints, 
and  through  crevices  in  the  tile  at  difierent  points  made 
pervious  by  the  action  of  the  fire. 

The  ditches  for  underdrains  should  be  constructed  jDar- 
allel  to  each  other,  from  20  to  40  feet,  according  to  the 
character  of  the  soil,  the  number  of  springs,  etc.  They 
should  be  four  or  five  feet  deep,  wide  at  the  top  and  narrow 
at  the  bottom. 

94.  Drainage  at  the  South, 
There  is  but  one  class  of  soils  at  the  South  that  will 
pay  for  draining:  lowlands  which  are  surcharged  with  bot- 
tom water.    The  object  here  is  not  to  improve  the  climate 
or  aid  chemical  action,  so  much  as  to  get  clear  of  the  super- 


132 


SOILS  AS  RELATED  TO  PHYSICS. 


incumbent  water,  which  acts  mechanically  as  an  obstrnc* 
tion  to  the  nutrition  of  plants. 

Much  of  this  ditching^  as  termed  at  the  South,  was  per- 
formed before  the  war;  but  since,  owing  to  the  paucity  of 
labor,  the  ditches  have  not  been  kept  open,  many  valuable 
bottoms  lost  to  cultivation,  and  malarial  fevers  have  become 
much  more  prevalent ;  for  one  great  advantage  of  draining 
a  country  is,  that  it  adds  to  the  salubrity  of  the  climate 
and  health  of  the  inhabitants. 

In  every  cultivated  field,  much  of  the  valuable  hillside 
soil,  as  well  as  manurial  substances,  are  washed  down  by 
rains  into  the  wet  bottoms;  and  where  there  is  much  water, 
the  land  is  but  little  improved,  as  the  soil  has  no  absorbing 
j^ower,  being  already  saturated.  Drainage  would  be  of 
great  benefit  in  this  regard ;  and  also  wliere  there  is  not 
much  water,  but  still  too  much  for  cultivation,  and  the  val- 
leys have  been  enriched  by  the  accumulation  of  ages. 
These  lands  once  well  ditched  and  properly  underdrained, 
would  pay  better  for  the  investment  than  any  portion  of 
the  farm.  Because  the  uplands  need  an  annual  outlay  of 
money  for  manures,  more  than  the  ditching  would  cost. 
When  once  done  as  it  should  be,  it  will  last  an  age  with- 
out fertilizers. 

While  it  is  true,  as  stated,  that  it  would  hardly  pay  to 
drain  uplands,  where,  in  most  cases,  there  is  a  scarcity  of 
water  during  the  summer,  yet  there  are  many  soils,  even 
among  this  class,  that  would  be  benefited,  because  of  their 
compactness  and  impermeability  to  air  and  water. 

Many  of  the  flat  lands  might  be  greatly  improved  by 
drainage,  but  we  must  wait  for  an  increase  in  their  value 
before  much  money  can  be  expended  in  this  way,  as  there  is 
quite  as  much  land  to  be  obtained  at  cheap  rates  (having 
every  natural  advantage)  as  there  is  labor  to  cultivate  them. 

95.    Of  TrencMng, 
Trenching  and  spading  are  very  useful  in  some  of  the 


OF  PLOUGHS. 


133 


older  countries,  where  land  is  high  and  human  muscle  can 
be  used  to  much  greater  advantage  than  with  us. 

There  are  two  valuable  ends  obtained  by  trenching 
which  it  is  proper  to  state  :  making  the  soil  porous  for  a 
greater  depth  than  can  be  attained  by  the  plough,  and 
bringing  up  from  the  subsoil  soluble  matters  that  have 
been  washed  away  for  ages,  and  depositing  them  on  the 
surface. 

The  practical  tests  of  it  in  this  country,  in  gardens  and 
vineyards,  have  2:)roven  very  clearly  that  it  will  not  pay. 
The  physical  benefit  to  the  soil  lasts  but  a  short  time,  as 
our  heavy  rains  cause  our  clay  soils  soon  to  assume  their 
former  compactness,  and  the  immense  outlay  required  pre- 
cludes all  hope  of  remuneration.  Hence  the  system  in 
this  country  has  been  abandoned  for  the  cheaper,  if  not 
more  efficient,  processes  of  the  plough. 


CHAPTER  VII. 

PLOUGHS.  PLOUGHING.  SUBSOILING.  HORIZONTAL 

CULTUKE. 

96.    Of  Ploughs, 

Of  all  the  mechanical  means  of  improving  the  soil, 
ploughing  is  the  most  important  and  efficient.  In  order 
to  do  this  it  is  very  essential  to  have  good  tools  properly 
constructed. 

Simplicity  in  mechanical  construction,  so  iniportant  in 
everything  else,  is  especially  so  in  reference  to  ploughs. 

For  turning  rough  lands,  such  as  we  have  at  the  South, 
being  often  rocky  and  rooty  and  stumpy,  the  common 
turning  shovel  is  the  best  implement.  It  breaks  deep, 
and  turns  very  well.    This  followed  by  a  good  subsoiler 


134 


SOILS  AS  EELATED  TO  PLANTS. 


will  prepare  land  well  either  for  corn  or  cotton;  and,  as 
is  the  case  in  most  instances  where  there  is  no  time  to 
subsoil,  this  plough  can  be  constructed  so  as  to  go  very- 
deep  as  well  as  turn  under  the  top  soil  at  the  same  time 
with  two  horses  attached. 

The  principal  objects  to  be  obtained  by  ploughing, 
are  to  turn  over  tlie  soil,  to  subsoil,  to  pulverize,  to  open 
for  planting,  to  cover  the  seed,  and  to  cultivate  the  plant. 
Here  are  six  different  objects,  all  of  which  require  a  dif- 
ferent iinjDlement. 

There  are  so  many  manufacturers  of  ploughs,  and  so 
many  good  ploughs  in  market,  and  such  a  diversity  of 
opinions  as  to  which  is  the  best,  that  we  leave  the  subject, 
adding  nothing  to  the  general  suggestions  given  above. 

97.  Benefits  of  Ploughing, 

There  are  two  good  reasons  why  land  should  be  turned 
over  at  least  once  a  year.  This  should  be  done  during 
the  autumn  or  winter.  You  bring  up  and  place  on  the 
surface  soluble  matters  that  have  leached  down  too  low 
for  the  feeders  to  reach,  and  you  cover  in  the  soil  the 
weeds,  grass,  and  stubble  of  the  gathered  crops,  where  they 
will  undergo  decomposition,  and  be  in  the  right  place  for 
the  rootlets  to  feed  upon.  The  tilth  is  deej^ened  also,  and 
if  some  of  the  clay  subsoil  is  thrown  on  top  it  becomes 
much  more  exposed  to  the  action  of  carbonic  acid  and 
oxygen,  which  disintegrates  it  more  effectually,  and  ren- 
ders its  particles  so  fine  as  that  solvents  may  act  upon  them 
much  more  readily. 

We  say  that  this  operation  should  be  performed  dur- 
ing fall  or  winter,  as  thereby  the  action  of  frost  upon  the 
clods  is  secured.  The  moisture  in  them  freezes  into  ice, 
which  expands  and  separates  the  particles  of  soil,  leaving 
them,  when  the  spring  opens  and  the  moisture  dries  out, 
much  better  pulverized  than  could  be  effected  by  mechan- 


BENEFITS  OF  PLOUGHING.  135 

ical  means,  and  in  a  finer  condition  for  absorbing  and 
retaining  ammonia  and  other  gases.  Besides,  the  organic 
matter  turned  in  and  lying  all  winter,  will  be  so  decom- 
posed as  to  furnish  considerable  nitrogenous  and  mineral 
food  for  the  next  summer  crops. 

It  will  always  be  advisable  to  cut  down  the  stalks  of 
corn  and  chop  them  in  two  before  the  plough,  and  beat 
down  the  cotton  stalks,  thereby  scattering  the  burs,  and 
having  them  covered  that  they  may  rot  during  the  win- 
ter. There  is  no  telling  the  amount  of  available  food 
which  may  be  acquired  in  this  way. 

Turning  over  land  in  the  spring  is  of  doubtful  utility, 
especially  if  the  soil  is  thin.  We  have  seen  land  injured 
for  the  growing  crop  by  having  the  surface  soil  buried  so 
deep,  and  so  much  of  the  hard  subsoil  put  on  top,  after 
the  w^inter  is  over,  that  the  plants  could  not  get  the 
benefit  of  what  little  soluble  matters  existed  in  the  soil. 
Spring  ploughing  should  be  conducted  with  reference  to 
mixing  thoroughly  the  soil  and  subsoil  of  the  autumn 
ploughing,  letting  it  remain  in  place,  and  deepening  as 
far  as  possible  the  tilth  beneath. 

Lands  should  be  well  pulverized  in  order  for  plants  to 
obtain  the  available  food  already  in  the  soil,  or  that  wdiich 
is  applied  as  manure.  One  great  reason  why  stable  ma- 
nure itself  is  often  so  ineffective,  and  even  injurious  in 
time  of  drought,  is  because  it  is  not  fine  enough.  So  well 
convinced  are  the  venders  of  fertilizers  in  Europe  of  tlie 
importance  of  pulverizing  soils,  that  they  often  with  their 
manures  furnish  ploughs  and  harrows  gratis,  that  they 
know  will  well  accomplish  this  end.  Clay  lands  that  have 
been  trodden  very  hard,  or  are  ploughed  too  soon  after  a 
rain,  are  apt  to  break  up  cloddy.  A  heavy  harrow,  if  pro- 
perly used,  will  pulverize  the  land  and  relieve  this  difficulty. 
In  sandy  soils  this  implement  is  rarely  needed. 

It  is  very  important  sometimes  to  bed  up  lands  in 


136 


SOILS  AS  RELATED  TO  PLANTS. 


order  to  keep  them  dry  and  warm  during  cold,  wet  springs. 
This  is  especially  true  of  cotton.  The  common  rooter 
subserves  a  good  purpose  to  lay  off  the  rows,  the  shovel 
to  open  for  the  deposition  of  fertilizers,  and  then  the 
rooter  to  cover,  and  the  turning  shovel  to  finish  the  bed. 
A  small  harrow  with  two  teeth  or  a  bull  tongue  are  the 
best  implements  for  covering  seed;  and  the  cotton  sweep 
the  best  cultivator  for  corn  or  cotton,  where  land  has  been 
properly  prepared.  With  it  much  more  land  can  be  culti- 
vated than  with  ordinary  ploughs,  with  much  less  damage 
to  the  growing  crop  ;  as  the  grass  is  effectually  ploughed 
up,  and  the  surface  soil  stirred,  and  the  crust  broken  for 
the  admission  of  air,  while  the  roots  of  the  plants  are  left, 
for  the  main  part,  uninjured. 

Another  great  benefit  of  ploughing,  not  heretofore 
noticed,  is  the  much  greater  surface  of  soil  which  it 
exposes  to  the  action  of  the  atmosphere.  A  smooth,  un- 
ploughed,  compact  soil  presents  but  one  surface  to  the  air. 
A  sod  well  broken  exposes  every  side,  or  nearly  so,  of 
every  particle  of  soil  as  deep  as  the  tilth  goes.  All  the 
interspaces  are  filled  with  atmospheric  air,  which  goes  to 
work  in  its  disintegrating  and  solvent  action,  and  very 
much  more  is  accomplished  than  when  a  soil  has  been 
unbroken.  For  a  similar  reason  it  is  requisite  to  plough 
most  crops  after  every  rain,  when  the  surface  soil  is  more 
or  less  beaten  down  and  rendered  almost  impervious  to 
air.  By  this  process  fresh  air  is  let  down  to  the  roots, 
and  the  benefit  obtained  is  perceptible  to  the  most  casual 
observer. 

Very  few  crops  are  ploughed  suflficiently.  As  a  general 
rule,  those  are  the  most  productive  which  are  ploughed 
the  most.  True,  great  caution  must  be  used,  especially 
in  the  latter  stages  of  corn,  and  after  the  fruit  begins  to 
form  on  cotton,  but  the  ground  must  be  kept  stirred  to 
produce  a  maximum  crop.    We  are  satisfied  from  actual 


SUBSOILIXG. 


137 


experiments  that  corn  will  recuperate  much  more  readily 
from  injury  to  the  roots  by  deep  ploughing  than  cotton. 
A  good  rule  for  both  is  to  plough  deep  the  first  and  second 
time,  and  use  the  surface  plough  in  all  the  after  cultiva- 
tion. 

98.  Suhsoiling, 

Several  advantages  grow  out  of  breaking  land  very 
deep,  or  what  is  generally  called  subsoiling.  The  roots 
are  enabled  to  penetrate  much  deeper  in  quest  of  food,  a 
greater  amount  of  atmospheric  air  (and  consequently  nitro- 
gen and  carbonic  acid)  is  held  in  the  soil ;  for  as  the 
plough  passes  on,  the  atmosphere  presses  into  every  inter- 
space behind  it,  and  a  soil  well  broken  twelve  inches  deep 
will  have  twice  as  much  of  these  valuable  gases  as  that 
only  broken  six  inches.  Besides,  it  causes  heavy  rains  to 
sink  rapidly,  preventing  too  much  water  from  injuring 
the  plants,  and  at  the  same  time  saves  rolling  lands  from 
washing  into  such  ugly  gullies  as  so  often  disfigure  our 
hillsides. 

Again,  subsoiling  lands  is  a  great  prevention  to  drought, 
by  holding  in  store  a  better  supply  of  hygroscopic  and 
capillary  waters,  enabling  the  latter  to  move  more  freely 
through  a  deeper  and  more  porous  tilth. 

In  1873  we  instituted  a  practical  test  of  the  advantages 
of  subsoiling  land  botli  for  corn  and  cotton.  For  the  lat- 
ter we  planted  one-fourth  of  an  acre,  subsoiled  12  inches 
deep,  4  feet  wide,  using  at  the  rate  of  300  lbs.  of  am- 
moniated  phosphate.  It  produced  at  the  rate  of  1,227  lbs. 
per  acre.  The  same  amount,  not  subsoiled,  by  its  side,  pro- 
duced 1,012  lbs.  The  first  paid  for  the  fertilizer  and  made 
a  clear  profit  of  $16.38  per  acre.  The  last  made  a  profit 
of  $7.03. 

Subsoiling  land  for  corn  was  tested  as  follows:  One- 
half  acre  was  planted  and  cultivated  precisely  the  same 
Avay,  with  a  small  amount  of  ammoniated  superphosphate 


138 


SOILS  AS  EELATED  TO  PLANTS. 


applied  in  each  hill.  The  corn  was  planted  in  rows  six 
feet  wide  by  three  in  the  drill:  one-fourth  acre  was  sub- 
soiled  12  inches  deep  just  previous  to  planting.  The  sub- 
soiled  plat  produced  at  the  rate  of  19.70  bushels  to  the 
acre.  That  not  subsoiled,  17.34  bushels.  The  overplus 
of  corn  made,  about  paid  for  the  extra  labor.  A  dry  year 
it  would  doubtless  have  paid  more. 

99.  Horizontal  Culture, 

One  of  the  greatest  difficulties  in  the  cultivation  of  roll- 
ing lands,  is  the  washing  olf  of  the  surface  soil,  and  the 
formation  of  gullies,  especially  where  corn  and  cotton  are 
the  principal  crops.  The  best  remedies  are  deep  plough- 
ing, hillside  ditching,  and  horizontal  culture,  which  may 
be  thus  described  : 

Beginning  at  the  summit  of  a  hill,  the  guide  rows  must 
be  run  some  twenty  or  thirty  paces  apart,  according  to  its 
steepness  or  irregularity.  Where  they  begin  on  a  decliv- 
ity, and  end  on  a  gentle  slope,  they  must  be  run  much 
nearer  than  where  there  is  more  or  less  uniformity  in  the 
steepness  of  the  hill. 

The  points  of  departure,  or  hedge  roios^  must  be  as  few 
as  possible,  and  well  selected.  On  hills  running  out  into 
a  valley,  like  a  promontory,  the  crest  of  the  hill  from  its 
summit  to  its  base  must  be  the  hedge  row.  The  hollow 
between  the  hills  should  form  another,  and  so  of  all  rapid 
curves  on  hills  or  in  valleys. 

A  straight  ditch  should  be  opened  in  every  considerable 
hollow,  to  carry  off  the  waters  of  heavy  showers,  as  it  is 
impossible  to  construct  long  horizontal  rows  around  such 
sharp  curves  and  protect  the  land  from  washing.  In  old 
fields,  gullies  are  already  formed  where  such  ditches  are 
required.  They  should  be  straightened  and  deepened,  how- 
ever, as  this  will  prevent  much  valuable  soil  from  being 
carried  off. 


nORIZONTAL  CULTURE. 


139 


As  a  general  rule,  guide  rows,  and,  of  course,  the  corn 
or  cotton  rows  between  them,  should  be  run  on  a  perfect 
level.  Rows  thus  constructed  hold  all  the  water  of  mod- 
erate rains,  and  prevent  any  washing  of  the  land.  Cotton 
beds  thus  saturated  with  water  from  a  considerable  shower 
will  retain  moisture  for  da^'s,  while  those  inclining  down 
the  hill  would  carry  off  the  falling  rain  in  the  furrows 
between,  and  leave  the  bed  dry  and  the  cotton  to  suffer. 

On  long  slopes,  where  washes  begin  and  form  small 
gullies,  after  heavy  showers,  the  first  hillside  ditch  should 
be  constructed.  Below  this  run  the  rows  on  a  level  as 
above,  and  where  the  break  begins  run  another  ditch.  By 
this  means  the  rows  will  all  be  run  on  a  level,  and  compa- 
ratively few  hillside  ditches  be  needed,  while  the  corn  or 
cotton  will  suffer  much  less  from  drought,  the  beds  hold- 
ing all  the  water  that  falls  upon  the  land,  except  in  super- 
abundant showers,  when  it  will  not  be  necessary  to  retain 
all. 

In  a  few  cases  (which  a  practical  eye  will  soon  detect) 
it  may  be  necessary  to  run  the  rows  with  a  slight  fall  to 
each,  in  order  to  stop  the  formation  of  gullies,  and  prevent 
the  land  from  being  washed  away.  It  then  becomes  a 
question  whether  the  hillside  ditches  should  not  be  in- 
creased and  enlarged,  and  the  rows  still  run  upon  a  level,' 
because  of  the  great  benefit  resulting  from  holding  all  the 
water  and  saturating  the  beds  during  a  dry  season. 

As  economy  of  time  and  labor  are  the  first  requisites  in 
every  good  system  of  agriculture,  it  becomes  necessary  to 
adopt  some  plan  for  levelling  the  rows  much  more  expedi- 
tious than  the  plumb-line  level,  as  used  in  the  construction 
of  hillside  ditches.  The  old  plan  was  to  take  a  stand  at 
one  hedge  row  with  a  spirit  level,  and  sight  round  the  hill, 
causing  stakes  to  be  placed  at  prominent  points,  as  a  guide 
to  the  ploughman.  But  this  process,  though  much  shorter 
than  the  other,  is  too  tedious  and  laborious. 


140 


SOILS  AS  RELATED  TO  PLANTS. 


The  best  plan  is  to  level  with  the  eye  in  the  following 
manner :  Go  ahead  of  the  ploughman,  either  on  foot  or 
horseback,  keeping  your  eye  intently  fixed  on  the  ground 
some  eight  or  ten  steps  in  advance.  A  practical  eye  can 
soon  learn  to  keep  on  a  level  round  the  hill  in  this  way ;  at 
least  near  enough  for  all  practical  purposes.  When  the 
guide  row  is  completed,  while  the  ploughman  is  laying  oli 
one  by  its  side,  you  can  go  down  the  hill  and  ride  round 
below  the  guide  row,  and  ascertain  by  keeping  your  eye 
fixed  on  the  point  above  you  in  a  direct  line,  and  looking 
backward  and  forward,  whether  the  row  is  level  or  not. 
By  practising  this  plan  a  short  time,  any  person  may  lay 
oflf  a  field  horizontally  almost  as  perfectly  as  with  a  level, 
and  in  one-tenth  the  time,  and  with  no  labor  whatever,  only 
the  walking  or  riding. 

The  guide  rows  being  thus  laid  off  on  a  level,  or  nearly 
so,  the  other  ploughs  follow  and  fill  up  the  interstices  be- 
tween them,  with  corn  or  cotton  rows  as  the  case  may  be. 
The  plan  is  to  lay  ofi"  half  by  the  guide  row  from  above, 
and  half  by  the  guide  row  from  below,  filling  out  with 
short  rows  in  the  middle,  which  should  be  a  little  narrower 
at  the  ends,  and  the  very  last  ones  wdder  in  the  middle. 

When  short  rows  are  run  to  fill  out  a  place  thrown  off 
of  a  line  by  irregular  slopes,  always  have  two  or  four  in- 
stead of  one  or  three,  as  this  will  be  found  to  save  time  and 
prevent  lifting  the  plough  back  to  the  starting  point,  both 
in  laying  off  rows,  and  in  ploughing  three  or  five  furrows 
to  the  row. 

This  plan  of  horizontal  culture  is  particularly  adapted 
to  larger  plantations,  by  which  time  and  labor  are  both 
economized.  It  will  be  found,  doubtless,  with  some  modi- 
fication, adapted  to  smaller  farms  wherever  lands  are  dis- 
posed to  wash. 


PAET  IT. 

CHEMISTRY  OF  THE  ATMOSPHERE. 


CHAPTER  I. 

COMPOSITION  OF  THE  ATMOSPHEKE.  OXYGEN.  OZONE, 

100.   Composition  of  the  Atmosphere, 

The  atmosphere,  Avhen  pure,  is  composed  of  two  gases, 
oxygen  and  nitrogen,  in  about  the  following  proportions: 

By  Weight.      By  Volume. 

Oxygen  23,17  20.95 

Nitrogen  76.83  79.05 

Other  substances,  as  w^ater,  carbonic  acid,  and  am- 
monia, occur  in  small  quantities,  of  which  we  will  speak 
more  fully  hereafter. 

Tlie  two  gases  of  which  the  atmosphere  is  mainly  com- 
posed are  combined  mechanically,  and  not  chemically,  as 
many  have  been  led  to  suppose.  There  is  a  general, 
though  not  exact,  uniformity  existing  between  these  gases, 
as  well  as  the  amount  of  carbonic  acid,  which  is  owing 
doubtless  to  the  even  balance  kept  up  between  the  life, 
growth,  and  decay  of  animal  and  vegetable  substances. 

Another  remarkable  fact  is,  that  these  gases  are  mixed 
in  uniform  proportions,  without  reference  to  their  specific 
gravity.  This  is  owing  to  a  law  of  nature  called  the  dif- 
fusion of  gases.  Whenever  two  gases,  although  of  dif- 
erent  Aveights,  are  brouglit  together  in  a  confined  space,  it 


142 


CHEMISTRY  OF  THE  ATMOSPHERE. 


will  be  found  that  they  gradually  intermingle,  until  they 
are  both  uniformly  diffused  throughout  the  place. 

If  a  volume  of  hydrogen  gas  is  introduced  into  an 
inverted  jar,  it  will  rise  at  once  to  the  upper  portion,  press- 
ing out  the  atmospheric  air  as  it  is  so  much  lighter. 
Now  introduce  a  volume  of  carbonic  acid  below  the 
hydrogen  gas,  which  is  fifteen  times  lighter  than  the 
other;  in  a  few  days  it  will  be  found  that  the  two  gases 
have  become  uniformly  mixed. 

There  are  some  gases  which  seem  to  be  an  exception  to 
this  rule,  as  the  carbonic  anhydride  (olefiant  gas),  which 
settles  at  the  bottom  of  old  w^ells,  and  is  very  deleterious  to 
animal  life. 

101.    Oxygen^  O. 

As  we  have  already  seen,  oxygen  constitutes  about  one- 
fifth  of  the  air,  and  exists  more  largely  in  all  living  plants 
than  any  other  element.  In  fact,  it  is  the  most  abundant 
body  in  nature — forming  in  combination  with  other  bodies 
about  one-third  of  all  the  soils  and  rocks  as  well  as  plants 
and  animals  of  the  globe,  and  eight-ninths  of  the  water 
of  its  rivers,  lakes,  and  oceans.  There  are,  in  fact,  but 
few  chemical  compounds  in  which  it  is  not  an  ingredient. 

Oxygen  forms  new  compounds  with  other  bodies,  hav- 
ing a  universal  tendency  to  this  kind  of  union.  Some  of 
these  combinations  are  called  acids^  as  with  carbon  it 
forms  carbonic  acid ;  others  are  oxides,  as  the  oxide  of 
iron.  In  the  processes  of  combination,  decay,  putrefac- 
tion, fermentation,  and  respiration,  it  is  being  constantly 
set  free — forming  new  compounds  by  its  chemical  affini- 
ties with  other  bodies. 

Although  oxygen  exists  in  the  atmosphere  in  an  un- 
combined  state,  it  is  impossible  to  obtain  it  pure,  except 
from  some  of  its  compounds,  as  chlorate  of  potash,  which, 
when  exposed  to  heat,  melts,  and  this  gas  escapes  in  abun- 
dance.   This  is  the  most  common  source  for  obtaining  it. 


OZONE — CONDENSED  OXYGEN, 


143 


As  oxygen  gas  is  a  great  supporter  of  combustion,  it 
will  increase  the  tlame  of  a  lighted  splinter  when  placed 
in  it,  and  instantly  restore  it  when  blown  out.  This  is  a 
good  test  for  it. 

The  burning  of  all  bodies  is  attended  with  a  chemical 
union  of  the  oxygen  of  the  air  and  the  body  being  con- 
sumed. The  increase  of  a  flame  depends  upon  an  increase 
of  oxygen.  The  reason  why  a  coal  of  fire  may  be  blown 
into  a  flame,  is  because  of  the  increased  amount  of  oxygen 
added  to  it,  and  not  from  any  supposed  virtue  in  the  force 
of  the  wind. 

Bodies  which  unite  slowly  with  oxygen  are  said  to 
oxidize,  as  the  decay  of  wood  and  rust  of  iron.  This  is 
a  species  of  combustion,  and  has  been  termed  by  Liebig 
eremacausis  (slow  burning). 

Free  oxygen  has  been  termed  vital  air^  as  animals  and 
plants  will  perish  in  its  absence.  It  is  introduced  into 
the  lungs  and  blood  by  the  act  of  breathing,  and  thence 
carried  throughout  the  system.  Thus  the  animal  heat  is 
kept  up,  and  the  waste  of  the  structure  replenished. 

102.    Ozone — Condensed  Oxygen, 

Ozone,  according  to  Faraday,  is  oxygen  in  an  active 
state  under  the  influence  of  electricity  or  in  combination 
with  it.  It  has  never  been  obtained  pure,  but  is  always 
found  mixed  with  several  times  its  weight  of  air  and 
oxygen. 

A  molecule  of  ozone,  as  demonstrated  by  Andrews, 
Babo,  and  Loret,  contains  more  atoms  than  ordinary  oxy- 
gen gas,  which  shows  that  this  element  diminishes  in 
volume  when  electrized.  Ozone  is  therefore  condensed 
oxygen, 

■This  disposition  of  elements  to  occur  in  two  or  more 
forms  is  called  allotropism..  Thus  carbon  is  found  as  dia- 
mond, plumbago,  and  charcoal;  and  phosphorus  exists  in 


144 


CHEMISTRY  OF  THE  ATMOSPHERE. 


two  forms,  red  and  colorless,  which  are  very  distinct  from 
each  other,  the  latter,  like  ozone,  having  much  more  vigor- 
ous tendencies  than  the  other. 

A  mixture  of  oxygen  and  ozone  has  been  prepared  by 
Babo  and  Glaus,  containing  6  per  cent,  of  the  latter.  It  is 
insoluble  in  water,  irritating  to  the  lungs,  and  destructive 
of  insect  life.    A  moderate  heat  will  destroy  it. 

103.  Sources  o f  Ozone. 

The  principal  sources  of  ozone,  as  far  as  know^n,  are 
atmospheric  electricity,  combustion,  and  slow  oxidation. 
If  it  be  true  that  it  is  also  produced  by  the  exhalation  of 
all  plants  in  sunlight,  it  Avould  seem  that  this  should  con- 
stitute its  principal  source.  But  however  rapidly  or  con- 
tinuously produced,  the  quantity  must  be  very  small,  as  it 
is  constantly  uniting  with  other  bodies  and  disappearing, 
and  cannot  manifest  its  peculiar  properties  only  as  it  is 
reproduced. 

Oxygen  is  converted  into  ozone  under  the  influence  of 
electricity,  when  jDcrfectly  pure ;  and  enclosed  in  a  glass 
tube  containing  moist  metallic  silver.  By  long-continued 
electrical  discharges,  the  oxygen  is  made  to  entirely  dis- 
appear, by  its  conversion  into  ozone  and  union  with  the 
silver,  which  gives  it  a  black  color.  On  heating  the  silver 
afterward,  the  same  quantity  of  oxygen  is  reproduced. 

The  white  vapor  which  rises  from  colorless  phosphorus 
when  half  covered  with  tepid  water  is  produced  by  the 
formation  of  ozone  mingling  with  other  substances;  as  not 
only  is  the  odor  manifest,  but  the  air  of  the  vessel  will  give 
to  iodide  of  potassium  starch  paper  the  blue  color  w^hich 
indicates  ozone. 

The  vigor  of  this  principle  is  manifest  when  it  is  known 
that  when  thus  formed  by  the  oxidation  of  phosphoi-us, 
only  Y^Vo  ^^^^  weight  of  the  air  is  composed  of  it ;  and 
yet  all  of  its  reactions  are  fully  seen.  (Johnson.) 


RELATION  OF  OZONE  TO  VEGETATION. 


145 


M.  Boillot  found  that  one  litre  of  pure  oxygen  treated 
with  electric  discharges  produced  seven  milligrammes  of 
ozone,  while  the  same  amount  of  air  gave  thirty-seven 
milligrammes  of  ozone. 

104.  Amount  of  Ozone  in  the  Atmosphere, 
Schonbien,  who  made  a  number  of  interesting  experi- ' 
ments  with  this  principle,  says  that  its  peculiar  odor  is 
distinctly  apparent  when  it  constitutes  only  one-millionth 
of  the  Aveight  of  the  air.  This  of  itself  would  indicate  that 
it  must  exist  in  very  minute  proportions,  as  it  is  very  rare 
that  its  odor  is  perceptible. 

Efforts  to  ascertain  the  amount  by  Zinenger,  Pless,  and 
Pierre,  as  a  constant  quantity,  have  varied  from  13  to  65 
million  parts  of  air  to  one  of  ozone. 

Atmospheric  ozone  is  most  abundant  in  winter,  as  the 
electrical  conditions  which  produce  it  are  the  greatest  at 
that  period,  and  in  more  northern  climates  the  snow  hides 
from  it  many  bodies,  with  which  it  would  otherwise  unite 
and  oxidize. 

105.  Relation  of  Ozone  to  Vegetation. 

As  to  the  effect  of  ozone  upon  vegetable  nutrition  we 
are  as  yet  almost  entirely  at  sea.  What  we  think  we  know 
is  only  inference  and  theory  at  most.  If  it  be  true,  how- 
ever, that  it  is  constantly  the  result  as  well  as  an  active 
agent  of  oxidation,  we  can  easily  perceive  how  it  is  con- 
nected with  the  processes  which  keep  up  vegetable  nutri- 
tion and  growth,  as  this  principle  of  oxidation  is  going 
on  by  day  and  by  night  in  all  soils  and  plants. 

Prof.  S.  W.  Johnson  has  a  favorite  theory  of  vegetable 
nutrition,  from  experiments  made  by  Schonbien  and  others, 
that  free  nitrogen  can  in  no  case  be  made  to  unite  with 
water,  but  that  it  does  enter  such  combinations  by  the 
action  of  ozone,  and  in  this  way  may  be  made  to  play  an 
important  part  in  vegetation. 
7 


146 


CHEMISTRY  OF  THE  ATMOSPHEEB. 


CHAPTEE  II. 

OF  HTDEOGEN. — CARBO^^^. — CARBONIC  ACID. 

106.  Hydrogen^  H. 

Hydrogen  gas  is  the  lightest  of  all  known  substances, 
being  fourteen  and  a  half  times  lighter  than  atmospheric 
air.  It  is  destitute  of  taste,  color,  or  smell.  It  constitutes 
one-ninth  part  of  water,  and  never  exists  free  in  nature, 
except  w^here  it  is  developed  from  pools  and  stagnant 
waters,  volcanoes  and  boiling  springs,  and  some  kinds  of 
rocks  and  limestones,  by  natural  chemical  action. 

Hydrogen  exists  rarely  in  the  mineral  world  except  in 
combination  w^ith  water.  It  is,  however,  a  constant  ingre- 
dient of  plants  and  animals,  and  of  most  substances  which 
enter  into  organic  life. 

Hydrogen  is  prepared  by  abstracting  oxygen  from  water 
by  substances  which  have  no  special  affinity  for  it :  as  so- 
dium, metallic  iron,  and  zinc. 

Owing  to  its  extreme  levity  it  is  used  for  filling  bal- 
loons, which  causes  them  to  ascend. 

Although  incapable  of  supporting  combustion  by  itself, 
hydrogen  inflames  when  brought  in  contact  with  a  lighted 
taper,  becoming  intensely  hot,  though  scarcely  luminous. 
The  air  in  contact  with  the  hydrogen,  keeps  up  the  flame, 
which  results  in  the  forming  of  jDrotoxide  of  hydrogen, 
which  is  the  universally  diffused  substance,  water. 

With  carbon,  hydrogen  forms  a  number  of  compounds, 
as  oil  of  turpentine,  oil  of  lemons,  the  volatile  oils,  etc. 
The  hydrocarbons  constitute  the  principal  illuminating 
ingredient  of  defiant  gas,  kerosene,  benzine,  and  paraffine. 

107.    Carbon,  C. 
Carbon  in  one  of  its  purest  forms  is  nothing  more  than 


CAEBON. 


147 


charcoal,  which  you  know  is  produced  by  burning  wood 
in  a  kiln  so  as  to  prevent  the  oxygen  of  the  air  from  unit- 
ing with  the  carbon  and  escaping  as  carbonic  acid  gas. 
Charcoal  generally  contains,  besides  carbon,  a  slight  admix- 
ture of  earthy  and  saline  matters. 

The  diamond  also  is  carbon  in  its  purest  form,  which, 
though  very  different  in  its  physical  features  and  value 
from  the  other  substances,  is  identical  in  a  chemical  sense, 
all  yielding  carbonic  acid  gas  upon  combustion. 

The  black  smoke  produced  in  the  burning  of  kerosene, 
lampblack,  anthracite,  and  black  lead  (plumbago),  are 
other  forms  of  carbon. 

Animal  charcoal  or  bone-black  is  also  an  impure  car- 
bon mixed  with  phosphate  of  lime.  It  is  produced  by  heat- 
ing bones  in  closely  covered  iron  pots,  and  is  used  for 
refining  sugar  ;  after  w^hich,  it  is  appropriated  to  the  man- 
ufacture of  superphosphates,  on  account  of  the  phosphoric 
acid  left  in  it. 

Porous  carbonaceous  substances  have  a  great  absorbing 
power  for  gases,  and  because  of  this  are  good  disinfectants. 
Charcoal  will  absorb  90  per  cent,  of  its  volume  of  ammo- 
niacal  gas. 

This  element  is  universal  in  all  vegetable  and  animal 
substances  ;  in  fact  no  organism  could  be  complete  with- 
out it.  Hence  it  may  be  deemed,  in  the  language  of  Prof. 
Johnson,  as  "the  characteristic  ingredient  of  all  organic 
compounds." 

When  uncombined,  carbon  is  solid,  and  can  only  be 
taken  up  as  plant  food,  or  volatilized  by  union  with  oxygen. 
This  combination  readily  takes  place  when  burned  in  the 
open  air.  Hence,  you  observe  that  ashes  are  always  white 
which  are  exposed  to  the  air  ;  while  those  parts  of  the  wood 
which  are  consumed  under  a  bed  of  ashes  make  charcoal, 
because  of  the  absence  of  oxygen  to  form  the  carbonic  acid 
gas. 


148 


CHEMISTRY  OF  THE  ATMOSPHERE. 


108.    Carbonic  Acid^  COg. 

Garhonic  acid  results  from  the  union  of  carbon  and 
oxygen,  and  is  one  of  the  most  important  principles  in  na- 
ture, especially  in  its  relations  to  vegetable  life. 

Twelve  grains  of  pure  carbon  heated  to  redness  in  32 
grains  of  oxygen  gas,  will  unite  and  form  44  grains  of  car- 
bonic acid  ;  being  one  equivalent  of  carbon  and  two  of 
oxygen — hence  the  formula,  COg. 

Whenever  any  organic  body  decays  or  is  burned,  car- 
bonic acid  is  formed  by  the  oxidation  of  carbon. 

Carbonic  acid  exists  very  extensively  in  nature.  Forty- 
four  per  cent,  of  this  acid  united  to  lime,  constitutes  all  the 
marble,  chalk,  and  common  limestones  of  the  earth,  under 
the  different  forms  of  carbonate  of  lime. 

There  are  other  carbonates,  as  of  potash  (saleratus)  and 
soda,  so  extensively  used  in  making  bread  :  also  carbonate 
of  ammonia,  which  exists  in  the  atmosphere,  and  is  brought 
down  by  the  rains,  constituting  an  important  fertilizer  to 
the  growing  crops. 

Carbonic  acid  exists  to  a  small  extent  in  all  fountain 
and  river  waters,  and  also  in  rain  water.  One  reason  why 
cold  spring  water  is  so  refreshing  is  owing  to  its  presence. 

109.    Qualities  and  Tests  of  Carbonic  Acid. 

Carbonic  acid  is  invisible,  having  a  slight  pungent 
odor,  is  half  heavier  than  atmospheric  air,  and  nearly  one- 
half  heavier  than  oxygen  gas. 

It  is  the  colorless  gas  which  causes  beer  and  soda  water 
to  effervesce  and  sparkle,  and  produces  the  frothing  of  por- 
ter and  ale. 

It  has  a  sour  taste,  and  reddens  vegetable  blues.  It  is 
very  soluble  in  water,  which  dissolves  more  than  its  bulk 
of  this  acid  as  106  is  to  100. 

As  carbonic  acid  is  so  much  heavier  than  the  air,  it  can 


CARBONIC  ACID  IN  THE  ATMOSPHERE.  149 


be  poured  from  one  vessel  into  another  like  a  fluid.  At  a 
temperature  below  72^,  it  becomes  solid,  forming  white 
crystals  similar  to  ice. 

Carbonic  acid  is  very  deleterious  to  animal  life.  The 
fumes  of  burning  charcoal  in  a  close  room  have  often 
proved  fatal  to  persons  sleeping  in  them,  by  this  gas  dis- 
placing the  oxygen  and  thus  producing  a  poisonous  air. 
When  it  reaches  15  to  20  parts  in  1,000,  it  produces  the 
distressing  efiects  of  headache,  giddiness,  stupor,  and  sufib- 
cation,  and  will  result  in  death  if  relief  is  not  alforded. 

Its  presence  may  be  easily  demonstrated,  by  fixing  a 
jar  of  lime  water  Avith  an  open  mouth,  thus  exposing  it  to 
the  air.  A  film  will  soon  form  upon  it,  which  results  from 
the  combination  of  the  carbonic  acid  of  the  atmosphere 
with  the  lime  held  in  solution. 

Another  way  to  test  the  presence  of  carbonic  acid  is,  to 
insert  a  reed  or  quill  into  lime  w^ater  and  blow  the  breatli 
through  it ;  a  milky  cloud  will  form  at  once  where  the 
carbonic  acid  of  the  breath  meets  with  the  lime  in  the 
water,  forming  carbonate  of  lime. 

It  is  thrown  ofi*  by  the  respiration  of  animals,  as  is 
proven  by  breathing  into  lime  water,  as  in  the  experiment 
above  mentioned.  The  burning  of  fuel  of  any  kind,  and 
the  decay  of  all  animal  and  vegetable  substances,  also  pro- 
duce it  in  immense  quantities. 

110.  Estimates  of  Carbonic  Acid  in  the  Atmosphere, 

In  300  analyses  of  the  atmosphere,  the  carbonic  acid 
ranged  from  46  to  86  parts  by  weight  in  100,000.  In 
round  numbers,  it  has  been  estimated  at  one  part  in 
12,000.  Though  this  is  a  small  amount  in  comparison 
with  the  whole  bulk  of  the  atraosphere,  it  is  nevertheless 
immense  when  taken  in  the  aggregate,  furnishing  an  un- 
failing supply  of  carbon  to  plants,  and  oxygen  to  animals. 

Prof.  Shultz,  of  Rostock,  by  recent  experiments  finds 


150 


CHEMISTEY  OF  THE  ATMOSPHERE. 


rather  less  carbonic  acid  than  heretofore  indicated  by  most 
observers.  He  detected  only  about  2.9  of  the  acid  in 
10.000  volumes  of  the  air,  being  less  than  one-third  per 
cent. 

While  he  found  no  variations  as  to  the  time  of  day 
or  year,  meteorological  phenomena  had  undoubted  influ- 
ence. Thus  a  snow-fall  would  increase  the  amount,  while 
rain  would  cause  a  decrease.  Northwest  winds  invari- 
ably augmented  the  amount,  while  southwest  winds  dimin- 
ished it. 

These  facts  led  Prof.  Shultz  to  infer  that  while  the 
average  percentage  was  kept  up  by  volcanic  exhalations, 
animal  respiration,  processes  of  decomposition  and  com- 
bustion, and  some  minor  causes,  the  sea  Avas  itself  a  con- 
stant absorbent  of  carbonic  acid  from  the  atmosphere. 

The  professor  is  now  engaged  in  endeavoring  to  learn 
to  what  this  absorptive  power  of- sea  water  is  due  ;  having 
already  ascertained  that  w^hen  it  boiled  it  absorbs  scarcely 
one-fourth  part  as  much  as  sea  water  which  has  lost  its 
carbonic  acid  by  the  action  of  hydrogen. 


CHAPTER  III. 

NITROGEN  AND  ITS  OXIDES. 

111.  Nitrogen^  N. 

Nitrogen^  as  we  have  seen,  constitutes  about  80  per 
cent,  of  the  atmosphere,  but,  without  a  proper  admixture  of 
oxygen,  instantly  extinguishes  flame  and  destroys  human 
life.  It  is  therefore  neither  a  supporter  of  combustion  nor 
respiration.  Its  office  in  the  atmosphere  seems  to  be  to 
dilute  and  temper  the  oxygen. 

Nitrogen  may  be  obtained  by  the  abstraction  of  oxy- 


NITRIC  ACID. 


151 


gen  from  the  atmosphere  by  any  body  which  is  very  com- 
bustible and  unites  readily  with  oxygen,  as  phosphorus  for 
instance.  This  gas  when  free  possesses  very  little  activity, 
being  characterized  by  its  chemical  indifference  to  most 
other  bodies.  It  was  formerly  called  azote  (against  life), 
because  animals  perish  when  confined  in  it. 

It  is  very  difficult  to  make  it  unite  with  other  bodies. 
With  oxygen  it  forms  nitric  acid,  and  with  hydrogen  am- 
monia, both  of  which  are  powerful  fertilizers.  At  a  high 
heat,  it  unites  with  carbon,  forming  cyanogen^  which  is 
found  in  Prussian  blue. 

Although  nitrogen  constitutes  so  large  a  portion  of  the 
air,  it  is  of  no  direct  benefit  to  vegetation  as  such  ;  nei- 
ther is  it  even  convertible  into  ammonia  by  the  direct 
union  with  hydrogen,  escaping  from  any  substances  con- 
taining: it. 

112.  Nitric  Acid.^O^. 

Nitric  acid  is  composed  of  one  equivalent  of  nitrogen, 
three  of  oxygen,  and  one  of  hydrogen. 

When  pure  it  is  colorless,  but  generally  is  a  yellow 
liquid,  sold  in  the  shops  as  aquafortis.  It  has  a  sour,  burn- 
ing taste,  penetrating,  suffocating  odor,  and  is  a  very  pow- 
erful corrosive  poison. 

It  is  volatile,  and  evaporates  when  exposed  to  the  air, 
not  as  rapidly  as  water,  however.  It  is  50  per  cent,  heavier 
than  its  own  bulk  of  water. 

Having  a  strong  affinity  for  water,  it  condenses  mois- 
ture, and  hence  when  its  vapors  rise  they  appear  in  white 
fumes  or  clouds. 

Nitric  acid  is  a  powerful  oxidizing  agent.  By  this 
process  it  loses  oxygen,  and  is  reduced  to  other  compounds, 
having  less  nitrogen ;  as  nitric  oxide,  nitric  peroxide,  and 
nitrous  acid. 

Boussingault,  Cloez,  and  De  Luca  have  abundantly 
proved  the  existence  of  nitric  acid  in  the  air  by  causing 


162 


CHEMISTRY  OF  THE  ATMOSPHERE. 


large  volumes  of  it  to  pass  through  solutions  of  potash, 
or  over  bricks  and  pumice-stone  saturated  with  it.  These 
absorbents  in  this  way  gradually  acquire  small  quantities 
of  it.  And  to  make  the  results  more  conclusive,  Cloez  and 
De  Luca  first  washed  the  air  of  its  ammonia  with  sulphuric 
acid. 

113.  Nitric  Peroxide^  NOo. 

Nitric  peroxide  (hyponitric  acid)  is  formed  from  free 
nitrogen  in  the  atmosphere  by  electrical  ozone.  This  was 
demonstrated  by  Schonbien  and  Meissner  by  experiments 
showing  that  a  discharge  of  electricity  through  dry  air 
would  cause  the  oxygen  and  nitrogen  to  unite. 

This  explains  experiments  made  by  Cavendish  as  early 
as  1784,  that  electric  sparks  transmitted  over  a  solution  of 
potash  in  moist  air  would  produce  nitrate  of  potash. 

114.   Generation  of  Nitric  Acid  in  the  Atmosphere, 

Formerly  it  was  believed  that  nitric  acid  was  present 
in  the  atmosphere  only  during  thunder-storms.  Way  and 
Boussingault,  however,  have  proved  by  analytical  investi- 
gation, that  this  principle  is  not  increased  by  visible  or 
audible  discharges  of  electricity,  the  rains  without  these 
manifestations  being  equally  as  rich  in  nitric  acid  as  others. 
In  fact,  Babo  and  Meissner  have  demonstrated  that  there 
is  more  of  it  developed  in  silent  electricity  than  when  at- 
tended with  flashes  and  detonation. 

Meissner  has  also  shown  that  the  electric  fluid  produces 
a  copious  formation  of  nitric  peroxide  in  its  path  by  reason 
of  the  heat  which  accompanies  it.  This  increases  the  en- 
ergy of  the  ozone  simultaneously  produced,  causing  it  to 
expand  into  the  oxidation  of  nitrogen. 

Another  method  by  which  free  nitrogen  of  the  atmo- 
sphere is  made  to  form  compounds  with  oxygen  and  hydro- 
gen, is  by  the  processes  of  combustion  and  slow  oxidation. 

Saussure  first  noticed  that  nitric  and  nitrous  acid  were 


NITRATES  AND  NITRITES. 


153 


formed  by  burning  a  mixture  of  oxygen  and  hydrogen 
together  in  the  air.  Subsequently  he  discovered  that  the 
water  resulting  from  this  process  contained  ammonia. 

Kolbe  also  produced  reddish-yellow  vapors  of  nitric 
j)eroxide,  by  a  jet  of  burning  hydrogen  communicating 
with  an  open  bottle  containing  oxygen.  This  was  pro- 
duced freely  as  soon  as  atmospheric  air  mingled  with  the 
burning  gases. 

Schonbien  was  the  first  to  observe  that  nitric  acid 
might  be  formed  at  ordinary  temperatures.  By  adding 
carbonate  of  potash  to  the  liquid  resulting  from  the  slow 
oxidation  of  phosphorus,  he  obtained  nitrate  of  potash. 

115.  Nitrates  and  Nitrites, 

The  nitrates  are  admitted  to  be  among  the  most  efficient 
means  through  which  plants  receive  their  nitrogen.  But 
although  generated  to  some  extent  in  the  atmosphere,  they 
are  never  imbibed  as  plant  food  by  the  leaves,  but  have 
necessarily  to  pass  into  the  soil,  and  are  taken  up  by  the 
roots.  We  will  therefore  defer  what  we  have  to  say  of  them, 
as  well  as  ammonia,  until  we  come  to  speak  of  fertilizers. 

There  is  generally  an  excess  of  ammonia  over  nitric 
acid  in  the  atmosphere;  there  being  a  strong  affinity  be- 
tween them,  doubtless  most  of  the  nitric  acid  as  soon  as 
produced  unites  with  the  ammonia,  forming  nitrate  of  am- 
monia, which  contains  more  soluble  nitrogen  than  any 
other  substance. 

As  the  nitrate  of  ammonia  is  not  volatile  like  the  car- 
bonate, it  is  probable  that  this  salt  may  be  held  in  a  state 
of  mechanical  solution  until  it  is  brought  down  by  the 
rains,  when  it  is  doubtless  soon  appropriated  as  plant-food. 

The  nitrates  and  nitrites  are  convertible  into  each  other, 
and  are  both  of  them  instantly  oxidized  by  ozone.  By  pro- 
longed action  both  of  these  classes  of  salts  may  be  trans- 
formed into  ammonia. 


154 


CHEMISTRY  OF  THE  ATMOSPHERE. 


116.  Nitric  Acid  in  Rain  Water, 

Inasmuch  as  a  small  bulk  of  rain  washes  a  large  volume 
of  air,  it  is  reasonable  to  suppose  that  the  rain  water  con- 
tains much  more  nitric  acid  than  the  air  itself.  Liebig  first 
found  nitrates  in  rain  water,  and  the  subsequent  investiga- 
tions of  Boussingault,  1856-8,  amply  confirmed  the  previous 
announcement  of  Barral,  that  nitric  acid  in  combination  is 
almost  invariably  present  in  fog,  dew,  rain,  hail,  and  snow. 
In  180  rains,  snows,  dews,  etc.,  Boussingault  found  only  16 
in  which  he  could  not  detect  nitric  acid. 

The  total  quantity  of  nitric  acid  detected  in  rains 
at  Rothemstead,  England,  by  Lawes,  Gilbert,  and  May, 
amounted  in  1855  to  2.98  lbs.,  and  in  1856,  2.80  lbs.  per 
acre. 

At  Insterburg,  Pincus  and  Rollig  found  in  the  rains 
which  fell  the  year  ending  March  1865,  7^  pounds  of  nitric 
acid. 

Bretschneider  found  in  488  gallons  of  rain  water,  eleven 
pounds  of  nitrogen,  equal  per  acre  for  one  year,  9.93  of 
ammonia,  and  of  nitric  acid  nearly  one  pound. 


CHAPTER  lY. 

AMMONIA,  YAPOR  OF  WATER,  AND  OTHER  INGREDIENTS 
OP  THE  ATMOSPHERE. 

117.  A7nmonia^  NHo. 

Ammonia  is  a  colorless  gas,  having  a  strong  pungent 
odor.  It  is  condensible  into  a  liquid  form,  under  a  pressure 
of  six  and  a  half  atmospheres  at  a  temperature  of  60^  F. 

It  is  composed  by  weight  of  hydrogen  8,  nitrogen  14  ; 
by  measure,  three  of  hydrogen  to  one  of  nitrogen.    It  is 


AMMONIA  IN  EAIN  WATEK. 


155 


alkaline  in  its  character,  and  denominated  by  the  early- 
chemists  the  volatile  alkali. 

Liquor  ammonia,  according  to  Faraday,  freezes  at  a 
temperature  of  75^  F.  into  a  colorless  solid,  heavier  than 
the  liquid  itself.  Water  dissolves  seven  hundred  times  its 
volume  of  this  gas. 

De  Saussure  says  that  boxwood  charcoal  absorbs  ninety- 
eight  times  its  volume  of  ammonia.  This  takes  place,  how- 
ever, according  to  Stenhouse,  by  cooling  hot  charcoal  in 
mercury  or  a  vacuum.  It  escapes  P9  rapidly  that  in  a  short 
time  only  minute  traces  of  it  are  found. 

118.  Ammonia,  in  the  Atmosphere, 

Ammonia  may  be  considered  as  a  permanent  ingre- 
dient of  the  air,  as  it  is  constantly  escaping  from  the  earth, 
being  generated  by  the  decaying  bodies  of  dead  animals, 
as  well  as  the  urine  and  excrement  of  living  ones,  and 
also  from  the  decay  of  vegetable  substances. 

Some  chemists  have  estimated  the  average  amount  of 
ammonia,  as  existing  in  the  atmosphere,  at  fifty-two  mil- 
lionths.  The  quantity,  however,  is  necessarily  variable, 
as  every  rain  brings  down  all  that  exists  between  the 
clouds  and  the  earth,  and,  for  the  time  being,  leaves  that 
part  of  the  atmosphere  bereft  of  it.  It  is  soon,  however, 
resupplied  on  the  principle  of  dilFasibility. 

Some  idea  may  be  given  of  the  small  amount  of  am- 
monia existing  in  the  atmosphere  by  a  calculation  of  Lie- 
big.  He  estimates,  that  if  all  the  ammonia  of  the  air 
was  brought  to  the  surface  and  compressed  into  one 
stratum,  it  would  not  be  one-fourth  of  an  inch  in  thick- 
ness. 

119.  Ammonia  in  Rain  Water, 

The  results  of  all  the  investigations  made  by  Boussin- 
gault.  Way,  Knop,  and  others,  as  to  the  amount  of  ammonia 
in  rain  water,  make  it  range  from  1  to  33  parts  in  ten  mil- 


156 


CHEMISTRY  OF  THE  ATMOSPHERE. 


lion.  This  applies  more  particularly  to  country  places.  In 
cities;  much  larger  estimates  have  been  obtained. 

Summer  showers  have  much  more  ammonia  in  them 
than  the  long-continued  winter  rains,  as  they  occur  fre- 
quently and  over  small  extents  of  country  ;  the  atmosphere 
being  resupplied  not  only  by  evaporation,  but  by  difFusi- 
bility.  Upon  this  j^rinciple  the  amount  of  ammonia  would 
be  nearly  equal  in  what  are  termed  local  showers,  and  thus 
the  amount  of  ammonia  which  a  crop  receives  from  the  rain 
may  be  estimated  according  to  the  amount  of  rain  w^ater 
precipitated. 

The  first  portion  of  a  shower  of  rain  that  comes  down 
contains  more  ammonia  than  the  last.  Boussingault  found 
66  parts  of  ammonia  in  the  first  tenth  of  a  slow-falling  rain, 
to  tqn  million  of  water  ;  and  in  the  last  three  tenths,  only 
13  parts. 

The  total  amount  of  rain-fall  at  Rothemstead,  England, 
in  1855,  as  estimated  by  Lawes  and  Gilbert,  and  analyzed 
by  Way,  contained  7  pounds  of  ammonia  for  an  acre  of 
surface  ;  and  in  1856,  9^  pounds.  The  estimated  amount 
of  rain  water  being  respectively  663,000  and  616,000  gal- 
lons. 

Pincus  and  RoUig  found  6.38  lbs.  of  ammonia  per  acre 
for  the  rain-fall  at  Insterburg,  in  1865;  and  Bretschneider 
at  Ida-Marienhutte,  the  same  year,  estimated  12  lbs.  of 
ammonia  for  each  acre  of  surface. 

120.  Relation  of  Atmospheric  Ammonia  to  Vegetation. 
The  ammonia  of  the  atmosphere,  although  of  small 
Bignificance  ^s  to  amount,  is  doubtless  of  much  benefit 
to  vegetation.  Escaping  as  free  ammonia  from  so  many 
different  sources,  it  unites  with  the  carbonic  acid  of  the  at- 
mosphere, forming  carbonate  of  ammonia,  which  is  volatile 
also,  and  remains  until  absorbed  and  brought  down  by 
rain  water. 


STEAM  OR  YAPOR  OF  WATER. 


167 


It  is  well  known  by  agricultural  chemists  that  ammonia 
(nitrogen)  has  the  peculiar  effect  of  imparting  a  rich  green 
color  to  foliage  when  it  occurs  in  notable  quantity.  The 
change  produced  in  the  blades  of  Indian  corn  after  summer 
showers  is  so  marked  in  this  regard,  that  it  is  clearly  infer- 
able that  it  does  not  result  exclusively  from  rendering 
soluble  ammoniacal  matters  already  in  the  soil,  but  by 
furnishing  ammonia  directly  to  them  brought  down  by 
the  atmospheric  waters. 

Liebig  attributes  (very  properly  we  think)  the  good 
effect  of  a  top-dressing  of  plaster  on  clover  to  ammonia 
which  has  been  absorbed  from  the  atmosphere  by  dews, 
mists,  and  rain.  The  ammonia,  having  a  stronger  affinity 
for  the  sulphuric  acid  than  lime,  takes  it  from  it,  and  forms 
sulphate  of  ammonia  ;  which  is  a  fixed  salt  and  very  solu- 
ble, being  carried  down  by  each  succeeding  rain  to  the 
roots  of  the  plants. 

121.  Steam  or  'Va2^07'  of  Wate7\ 
Steam  is  composed  of  two  volumes  of  hydrogen  and  one 
of  oxygen,  condensed  into  two  volumes,  its  specific  grav- 
ity being  0.625.  It  is  volatile,  and  rises  in  the  air,  and  in 
a  vacuum,  according  to  the  same  law  by  w  hich  gases  diffuse 
through  each  other.  Dalton  discovered  that  the  evapora- 
tion of  water  has  the  same  limit  in  air  as  in  a  vacuum. 
Hence,  in  order  to  determine  the  quantity  which  rises  in  a 
vacuum,  it  is  only  necessary  to  determine  the  quantity 
which  rises  in  air. 

Evaporation  is  not  simply  an  escape  of  liquid  water,  as 
many  suppose.  Into  the  air,  inasmuch  as  water,  as  such, 
cannot  remain  in  the  air.  It  would  fall  by  its  own  gravity. 
But  in  the  act  of  evaporation  a  chemical  change  takes 
place ;  the  w^ater  is  converted  into  vapor,  three  volumes 
being  condensed  into  two;  and  thus  it  becomes  a  part  of 
the  atmosphere. 


158 


CHEMISTRY  OF  THE  ATMOSPHERE. 


Steam  exists  in  the  atmosphere  in  an  average  of  about 
one  per  cent.;  although  it  is  quite  variable,  being  sometimes 
found  as  high  as  three  and  a  half  per  cent. 

Yapor  is  beneficial  to  vegetation  only  as  it  is  absorbed 
by  the  soil,  and  enters  through  the  roots ;  as  there  are  no 
well-authenticated  facts  to  prove  that  it  is  ever  imbibed 
by  the  leaves  of  agricultural  plants. 

Certain  air  plants  (epiphytes),  which  have  no  connec- 
tion with  the  soil,  are  known  to  imbibe  moisture  from  the 
atmosphere.  Mosses  and  lichens  also,  which  are  dry  and 
crisped  when  there  is  but  little  moisture  in  the  air,  become 
pliable,  and  show  signs  of  vigor  and  growth,  as  soon  as  the 
atmospheric  vapors  are  known  to  increase. 

122.    Other  Atmospheric  Ingredients, 

Quite  a  number  of  other  ingredients  have  been  men - 
tioned  by  authors  as  being  contained  in  the  atmosphere. 
Among  them  are  Marsh  Gas,  Carbonic  Oxide,  Nitrous  Oxide, 
Hydrochloric  Acid,  Sulphurous  Acid,  Sulphydric  Acid, 
Organic  Vapors,  and  suspended  solid  matters.  (How  Crops 
Feed,  p.  91.) 

None  of  these,  however,  if  we  except  the  last,  occur  in 
such  quantities  as  to  be  of  any  interest  to  the  agriculturist. 
In  fact  they  may  be  all  put  down  as  existing  accidentally, 
not  constantly,  in  the  atmosphere. 

123.    Organic  Matters  of  the  Atmosphere, 

Solid  matters  suspended  in  the  atmosphere  assume  some 
interest  under  recent  investigations  made  by  M.  Tissandier, 
wlio  analyzed  rain  water  which  fell  in  Paris  on  the  1st  and 
8th  of  July,  1870,  and  found  that  a  litre  of  water  contained 
0.0658  grams  of  dry  solid  residue;  containing  insoluble 
mineral  matters,  0.0108  grams  ;  insoluble  organic  matter, 
0.034  grams  ;  soluble  salts,  0.021. 

This  rain  water  was  found  to  contain  0.02  grams  of 


OKGANIC  MATTERS  OF  THE  ATMOSPHERE. 


159 


nitrate  of  ammonia.  As  this  salt  contains  35  per  cent,  of 
nitrogen,  it  follows  that  10  millimetres  of  rain-fall  carried 
down  70  grams  of  nitrogen  to  one  hectare  of  land,  besides 
the  organic  matter. 

If  this  analysis  represents  rain  water  generally,  the  old 
idea  of  its  being  approximately  pure,  and  answering  for 
distilled  water  in  many  cases,  is  exploded.  Its  value  as  a 
fertilizer  also  is  greatly  enhanced. 

Barral  and  Robinet  also  profess  to  have  discovered 
phosphoric  acid  in  rain  water  in  1862.  Luca  obtained  the 
same  result  from  w^ater  taken  from  near  the  surface  of  the 
earth,  but  at  a  height  of  60  or  more  feet  found  none. 

It  is  supposed  that  these  organic  matters  are  small  par- 
ticles of  impalpable  dust,  carried  by  the  winds  to  such  a 
height  that  they  are  not  influenced  by  gravitation.  It 
is  believed  that  these  substances  impart  the  whitish  hazy 
appearance  to  the  sky  so  often  seen  in  dry  windy  weather. 
And  when  it  assumes  its  deep  blue  color,  it  is  evident  that 
these  organic  particles  have  become  saturated  with  watery 
vapor  and  fallen  to  the  earth.  This  is  confirmed  in  the 
fact,  that  such  a  change  in  the  color  of  the  sky  generally 
precedes  rain,  being  an  evidence  of  greatly  increased  mois- 
ture in  the  atmosphere. 


PAET  Y. 


CHEMISTRY  OF  PLANTS. 


CHAPTER  I. 

ORGANISM  OF  PLANTS.  HYDROGEN  AND  NITROGEN  IN  THEM. 

124.    Organic  and  Inorganic  Constituents, 

All  plants  are  composed  of  two  classes  of  substances — • 
the  first,  combustible  and  volatile ;  the  second,  incom- 
bustible and'fixed. 

When  any  vegetable  product  is  subjected  to  a  high 
heat,  that  portion  which  disappears  in  invisible  gases  ris- 
ing and  mingling  with  the  atmosphere,  is  called  combus- 
tible ;  that  which  remains  as  ash,  incombustible. 

They  have  also  been  termed  organic  and  inorganic, 
because  the  organic  matters  which  constitute  the  vital 
growth  and  organization  of  plants  and  animals  are  mostly 
combustible;  and  the  inorganic,  which  constitute  the  bases 
of  all  minerals,  rocks,  and  salts,  are  incombustible. 

In  a  very  just  sense,  the  whole  of  a  plant,  embracing 
the  mineral  elements  as  well,  constitute  its  organism.  It 
is  only  then  in  a  restricted  sense  that  the  mineral  portion 
is  called  inoi-ganic.  They  constitute  so  small  a  portion 
of  plants,  that  the  early  chemists  regarded  them  as  rather 
accidental  than  otherwise.  With  the  exception  of  very 
minute  portions  of  sulphur  and  phosphorus,  they  exist 
outside  of  the  true  organic  compounds,  or  proximate  prin- 
ciples of  plants. 


OUGANISM  OF  PLANTS. 


161 


The  organic  and  inorganic  parts  of  plants  may  be  dis- 
tinguished from  each  other,  thus  : 

1.  Fire  destroys  the  organic,  but  cannot  affect  the 
inorganic. 

2.  The  first  decompose  under  the  influence  of  warmth 
and  moisture  ;  while  the  latter  retain  their  elementary 
integrity. 

3.  Organic  compounds  cannot  be  made  out  of  simple 
elements  by  chemists,  while  they  can  build  up  the  most 
complex  and  beautiful  crystals  out  of  inorganic  material. 

125.  Relative  Amount  of  each  in  Plants, 

It  is  estimated  that  organic  substances,  including 
water,  constitute  about  ninety-five  per  cent,  of  all  living 
plants,  leaving  from  one  to  five  per  cent,  of  ash.  While 
the  actual  amount  of  these  substances  found  in  plants 
differs  essentially,  according  to  their  age,  the  season  in 
which  they  grow,  and  the  character  of  the  plant ;  yet  an 
approximation  to  the  general  average  may  be  arrived  at 
by  comparing  a  number  of  estimates. 

Wolff  and  Knop  give  the  following  percentage  from  all 
the  trustworthy  analyses  made  of  agricultural  plants;  all  of 
them  air-dried,  except  the  last : 

Water       Organic  * 
water.  Matter. 

Average  of  all  the  grasses  14.3  79.9  5.8 

"       of  grains  and  seeds .  . .  14.2  83. 3  2.5 

of  straw  14.4  80.2  5.4 

of  chaff  and  hulls  . . .  .13.7  77.7  8.6 

of  roots  and  tubers. .  .85.7  13.4  0.9 

of  green  fodder  79.5  18.8  1.7 

126.    Organism  of  Plants, 

Organic  matter  may  be  either  structural  (made  up  of 
cells,  fibres,  and  tubers,  as  wood  and  flesh) ;  or  non-struc- 
tural— mere  results  of  the  nutritive  processes  of  animal 
and  vegetable  life,  as  sugar  and  fat. 


162 


CHEMISTRY  OF  PLANTS. 


While  combastion  and  decay  will  disorganize  organic 
substances  and  render  them  inorganic,  vegetable  growth 
will  reorganize  these  substances,  and  render  them  organic 
again.  Thus,  when  a  piece  of  wood  is  burned  at  a  high 
heat,  the  carbon  which  constitutes  the  principal  part  of 
its  bulk  unites  with  oxygen  and  flies  off  into  the  atmo- 
sphere, becoming  an  inorganic  gas.  It  may  be  again 
appropriated,  however,  by  plants,  and  become  solid  organic 
w^ood  or  flesh,  in  proper  combinations. 

There  are  many  bodies  which  are  organic,  but  do  not 
enter  properly  into  the  structural  organism  of  plants,  that 
leave  no  ash  when  burned  ;  such  as  dextrine,  sugar,  and 
oxalic  acid. 

127.   The  Four  Organic  Elements  in  Plants, 

If  the  invisible  gases  which  escape  ii'om  burning  w^ood 
and  other  vegetable  substances  are  gathered  in  a  retort 
and  analyzed,  they  will  be  found  to  consist  of  four  simple 
elements,  viz.  Carbon,  Hydrogen,  Nitrogen,  and  Oxygen. 

Carbon,  being  solid,  never  enters  the  roots  or  leaves  of 
plants  except  in  combination  with  oxygen  as  carbonic 
acid  gas. 

As  hydrogen  exists  in  the  atmosphere  only  in  vapor, 
and  never  in  the  soil  in  an  uncombined  state,  it  does  not 
enter  the  roots  or  leaves  of  plants  in  a  free  state,  but  in 
combination  as  water  or  ammonia. 

It  is  a  well-established  fact,  that  oxygen  enters  plants 
in  carbonic  acid  both  from  the  soil  and  the  atmosjDhere. 

It  is  not  believed  that  nitrogen  is  ever  appropriated 
by  plants  as  a  simple  element,  but  always  in  combination 
as  ammonia  or  nitric  acid. 

Oxygen  is  present  also  in  the  ash  of  plants,  associated 
with  phosphorus,  sulphur,  and  iron. 

Carbonic  acid  also  exists  in  certain  carbonates,  as  it 


OXYGEN  IN  PLANTS.  J  63 

takes  the  place  of  some  of  the  organic  acids  during  the 
jDrocess  of  combustion. 

Hydrogen  is  never  present  in  the  ash  of  plants,  where 
the  burning  has  been  complete  and  perfect. 

Nitrogen  occurs  under  certain  conditions  united  with 
carbon  as  a  cyanide  in  the  ash  of  plants.  In  order  to  effect 
this  the  temperature  must  be  very  high,  and  the  carbon  in 
excess.  Potassium  or  calcium  are  the  bases  with  which  the 
union  most  generally  takes  place.  This  combination  occurs 
naturally  in  only  one  common  plant,  viz.  the  oil  of  mustard. 

All  of  the  nitrogen  and  hydrogen,  and  much  of  the 
oxygen  and  probably  carbon  of  plants,  are  furnished  them 
directly  from  the  soil. 

For  while  it  is  true  that  solid  mineral  substances  do 
not  exist  in  the  atmosphere,  owing  to  their  ponderosity,  it 
is  equally  true  that  all  of  the  atmospheric  elements  exist 
in  large  quantities  in  the  soil. 

It  may  then  be  safely  estimated,  that  at  least  one-half 
of  all  the  substances  of  which  the  vegetable  world  is  com- 
posed comes  directly  from  the  earth. 

128.    Oxygen  in  Plants, 

Oxygen  is  found  in  the  ash  as  well  as  in  the  volatile 
parts  of  plants,  uniting  with  all  the  inorganic  elements 
which  enter  into  living  plants,  except  chlorine. 

Experiments  made  by  Traube  show  that  free  oxygen 
is  essential  to  the  growth  of  the  seedling  plant,  exciting 
the  plumule,  and  the  parts  which  are  in  the  act  of  elonga- 
tion. It  is  probable  that  oxygen  is  the  principle  which 
starts  the  vital  jDrocess  in  the  germ,  when  moisture  and 
heat  expand  and  burst  the  capsule. 

De  Saussure  proved  that  oxygen  gas  was  consumed  by 
the  buds  of  trees  in  the  following  manner:  He  took  willow 
and  apple  twigs  with  fresh  buds  and  placed  them  under  ^ 
bell-glass  set  in  water,  so  as  to  cut  off  the  outer  air,  Sub- 


164 


CHEMISTRY  OF  PLANTS. 


sequent  analyses  proved  that  the  oxygen  was  consumed 
by  the  buds.  In  a  mixture  of  nitrogen  and  hydrogen  gas, 
they  decayed  without  any  signs  of  vegetable  grov^^th. 

He  also  found  that  free  oxygen  w^as  absorbed  by  tlie 
roots  of  a  young  horse-chestnut  which  was  carefully  taken 
from  the  earth  and  placed  in  a  bottle  partly  filled  with 
water,  and  then  hermetically  sealed  around  the  stem. 
The  plant  flourished  for  three  weeks,  as  did  two  others 
similarly  treated  ;  while  other  plants,  placed  separately  in 
carbonic  acid,  nitrogen,  and  hydrogen,  perished. 

Flower  buds  consume  in  twenty-four  hours  many  times 
their  bulk  of  oxygen  gas. 

Free  oxygen  does  not  simply  act  as  food  for  plants,  but 
also  aids  in  assimilating  other  substances,  which  the  roots 
absorb  or  the  leaves  organize  for  the  tissues  of  growing 
plants. 

Traube  found  in  the  germination  of  seed,  that  when  the 
tip  of  the  plumule  an  inch  in  length  was  coated  with  oil 
thickened  with  chalk,  so  as  to  cut  off  a  supply  of  free  oxy- 
gen, the  seedling  stopped  growing  at  once,  withered,  and 
perished. 

As  a  further  proof  that  free  oxygen  must  have  access  to 
the  growing  part  of  a  plant,  Traube  varnished  one  side  of 
the  stem  of  a  young  pea  vine.  The  uncoated  side  contin- 
ued to  enlarge  and  extend,  while  the  other  ceased  to  grow 
— which  produced  a  curvature  in  the  stem. 

129.  Effect  of  Light  on  the  Transmission  of  Oxygen, 

It  has  been  proved  by  experiments  that  the  leaves  and 
green  parts  of  plants  absorb  and  exhale  oxygen  during 
their  exposure  to  light. 

If  you  invert  a  glass  funnel,  and  fill  it  wnth  fresh  lecves, 
placing  it  in  a  wide  glass  vessel  containing  water,  so  that 
it  is  completely  immersed,  having  expelled  the  air  from  its 
interior  by  agitation,  and  making  the  neck  of  the  funnel 


IIYDKOGEA^  IN  PLANTS. 


165 


air-tight  with  a  cork,  then  pour  off  a  portion  of  the  water 
from  the  outer  vessel,  and  expose  the  leaves  to  a  strong 
sunlight;  minute  bubbles  of  air  will  soon  gather  on  the 
leaves,  which  will  graduall}^  increase  in  size  and  detach 
themselves,  so  that  in  an  hour  or  two  enough  gas  wdll 
accumulate  in  the  neck  of  the  funnel  to  enable  you  to 
demonstrate  that  it  is  pure  oxygen. 

This  can  be  done  by  bringing  the  w^ater  inside  and  out- 
side the  neck  of  the  funnel  to  a  level,  having  the  end  of  a 
pine  splinter  glowing  hot,  but  not  in  a  flame,  inserted  into 
the  gas  upon  the  removal  of  the  cork.  The  gas  will  at 
once  become  inflamed,  and  burn  much  more  brightly  than 
in  atmospheric  air. 

De  Saussure  and  Grischow  found  that  green  plants  emit 
carbonic  acid  in  the  dark,  and  at  the  same  time  absorb 
and  appropriate  oxygen.  During  this  process,  it  has  been 
ascertained  that  the  volume  of  air  undergoes  diminution; 
which  shows  that  the  quantity  of  ox3'gen  gas  absorbed 
must  be  greater  than  the  volume  of  carbonic  acid  separated. 

In  no  case  has  it  been  known  that  oxygen  gas  has  been 
exhaled  from  plants  in  the  absence  of  light. 

It  is  a  known  fact  that  the  leaves  of  plants  absorb  oxy- 
gen during  the  night ;  and  it  has  been  proven  by  actual 
experiments  that  both  oxygen  and  carbonic  acid  are  ab- 
sorbed by  their  roots.  This  can  be  demonstrated  by  par- 
tially filling  a  bottle  w^ith  water,  saturated  with  carbonic 
acid  gas,  and  inserting  the  roots  of  a  growing  plant  in  it. 
The  carbonic  acid  of  the  water,  as  well  as  the  oxygen  of  the 
atmosphere  in  the  bottle,  will  gradually  diminish.  While 
if  the  atmospheric  air  is  substituted  by  the  carbonic  acid, 
or  by  nitrogen  or  hydrogen,  the  plants  will  speedily  die, 
showing  the  importance  of  oxygen  to  their  vitality. 

130.  Hydrogen  in  Plants, 
It  is  doubtless  through  water  that  plants  receive  most 


1G6 


CHEMISTRY  OF  PLANTS. 


of  their  hydrogen.  In  the  interior  of  plants,  this  water  is 
constantly  undergoing  decomposition,  and  in  this  way 
hydrogen  is  supplied  to  them. 

Another  source  of  hydrogen  to  plants  is  ammonia, 
which  is  a  combination  of  hydrogen  and  nitrogen,  and  one 
of  the  most  powerful  fertilizers  known.  While  this  is 
owing,  no  doubt,  to  the  nitrogen  it  contains,  its  hydrogen 
is  also  appropriated  we  doubt  not. 

Light  carburetted  hydrogen  gas  contains  about  one- 
fourth  of  its  weight  of  this  element,  and  is  known  to  be 
freely  evolved  from  the  decay  of  vegetable  matter  in  the 
soil.  This  probably  may  be  another  source,  both  of  carbon 
and  hydrogen,  to  plants,  as  their  roots  are  known  to  take 
up  gaseous  substances  in  the  soil. 

131.  Nitrogen  in  Plcmts, 

Nitrogen  is  a  constant  ingredient  of  all  plants,  and  of 
the  muscles,  tendons,  nerves,  etc.,  of  animals;  hence  all 
nutritive  food  has  in  it  larger  or  smaller  quantities.  It 
will  not  average  in  plants  more  than  from  two  to  three 
per  cent,  and  yet  no  plant  can  exist  without  it. 

Notwithstanding  the  atmosphere  is  the  great  store- 
house of  nitrogen,  yet  plants  never  imbibe  it  from  the  air; 
it  only  reaches  them  through  the  soil,  and  then  never  as 
nitrogen,  but  either  as  nitric  acid  or  ammonia. 

Deherain,  having  conducted  a  number  of  experiments 
in  reference  to  the  relation  of  the  nitrogen  of  the  atmo- 
sphere to  vegetation,  arrives  at  the  following  conclusions  : 

"First,  that  in  the  course  of  the  slow  combustion  of 
organic  matter,  the  nitrogen  of  the  atmosphere  enters  into 
combination,  j^robably  to  form  nitric  acid,  which,  in  con- 
tact with  an  excess  of  carbonized  matter,  is  reduced  and 
then  gives  up  nitrogen  to  the  organic  matter. 

"  Second,  that  every  plant  which  throws  off  refuse  mat- 
ter upon  the  soil  which  sustains  it,  furnishes  the  occasion  of 


PLANTS  DO  yOT  ABSOEB  OR  EMIT  XITEOGEX. 


IG7 


a  greater  or  less  tixation  of  nitrogen.  This  reaction,  con- 
tinued for  many  years,  ultimately  produces  the  accumula- 
tion, in  soils  left  to  themselves,  of  a  quantity  of  nitrogen 
sufficient  to  maintain  a  large  crop  of  cereals.*' 

Xitric  acid  and  ammonia  are  both  formed  in  the  atmo- 
sphere in  minute  quantities,  and  brought  down  to  the  earth 
by  rains,  and  thus  appropriated  as  food  for  plants. 

The  average  fall  of  nitrogen  in  atmospheric  waters, 
allowing  that  all  should  be  retained  and  appropriated  by  the 
crop,  would  suffice  to  make  about  one-half  a  crop  of  wheat, 
and  one-third  of  a  crop  of  cotton.  But  when  it  comes  to 
high  farming,  this  amount  would  have  to  be  tripled  and 
cpiadrupled. 

For  nine  years,  at  six  difierent  stations  in  Prussia,  the 
average  fall  was  9.06  lbs.  per  acre.  On  this  basis,  the 
amount  of  nitrogen  contained  in  an  average  crop  of  wheat, 
say  9^  bushels  and  1  cwt.  of  straw,  would  be  15.11  lbs.  In 
the  whole  of  the  cotton  plant,  to  make  500  lbs.  of  seed  cot- 
ton per  acre,  which  may  be  put  down  as  a  fair  average  crop 
according  to  the  best  analyses  we  have  (which  are  very 
imperfect),  the  amount  of  nitrogen  would  be  2Tf  lbs. 

132.  Plants  do  not  Absorb  or  Enut  Xltrogen. 

As  early  as  1779,  Dr.  Priestly  gave  it  as  his  opinion  that 
plants  absorbed  nitrogen  from  the  atmosphere.  Twenty 
years  later,  De  Saussure  experimented  on  the  subject  and 
arrived  at  a  differeiU  conclusion.  In  1S51  it  was  satisfac- 
torily demonstrated  by  Boussingault  that  plants  received 
no  nitrogen  as  food  in  this  way.  M.  Vilie,  however,  about 
the  same  time  experimented  on  a  larger  scale,  and  came  to 
a  difierent  conclusion.  In  1S54,  Boussingault  repeated  his 
experiments  with  moi'e  satisfactory  results  than  before. 

Subsequently,  31.  Cloez,  who  was  employed  by  the 
French  Academy  to  supervise  a  repetition  of  the  experi- 
ments of  M.  Ville,  found  that  o.  quantity  of  arnntonia  icas 


163 


CHEMISTKY  OF  PLANTS. 


either  generated  or  introduced  into  the  apparatus^  which 
vitiated  cdl  his  results. 

If  any  doubts  had  remained  of  the  correctress  of  Bous- 
singault's  conclusions,  they  were  entirely  removed  by  the 
researches  of  Lawes,  Gilbert,  and  Pugh,  in  1857  and  '58, 
at  Rothemstead,  England.  They  conducted  twenty-seven 
experiments  on  graminaceous  and  leguminous  plants,  and 
on  buckwheat;  and  confirmed  the  fact  previously  demon- 
strated by  Boussingault,  that  plants  do  not  absorb  nitro- 
gen from  the  atmosphere.  These  experiments,  curious  and 
interesting  in  themselves,  may  be  found  in  an  elaborate 
memoir  prepared  by  them  in  the  Philosophical  Transactions 
for  1861. 

Another  error  entertained  by  some  of  the  early  vege- 
table physiologists,  that  nitrogen  is  emitted  in  small  quan- 
tities by  plants,  was  clearly  proven  to  be  untrue  by  Cloez 
and  Boussingault  as  late  as  1863  and  1865. 


CHAPTER  XL 

RELATION  OF  CARBON  AND  CARBONIC  ACID  TO  PLANTS,  ETC. 

133.    Carhon  in  Plants, 

Carbonic  Acid  is  found  in  the  ash  of  plants,  combined 
with  bases  which  were  united  in  the  living  plant  wdth  or- 
ganic acids.  These  liavingbeen  expelled  by  the  heat,  are 
replaced  by  this  more  incombustible  acid.  The  amount 
of  it  found  in  ash  depends  on  the  temperature  produced 
in  the  analysis.  It  occurs  in  many  other  plants  as  a  car- 
bonate of  lime. 

In  1840,  Boussingault  proved  that  the  foliage  of  plants 
absorbed  carbonic  acid  from  the  atmosphere,  and  was 
nourished  thereby.    He  caused  a  current  of  air  with  about 


EFFECT  OF  SOLAR  LIGHT. 


IGO 


rAu  carbonic  acid  to  pass  into  a  vessel  having  three 
tubes,  one  of  them  containing  the  branch  of  a  living  vine 
which  had  borne  twenty  leaves,  the  tube  being  sealed  round 
the  stem  so  as  to  admit  uo  air.  This  air,  after  passing  into 
one  tube  over  the  leaves  ac  the  rate  of  fifteen  gallons  an 
hour,  passed  out  at  a  third  tube  into  an  arrangement  for 
collecting  and  weighing  the  carbon/  "  acid  gas.  It  was 
found  that  in  sunlight,  the  leaves  consumed  three-fourths 
of  the  carbonic  acid. 

Plants  purify  the  air  by  taking  up  carbonic  acid,  and 
throwing  off  oxygen.  Animals,  on  the  other  hand,  inhale 
and  appropriate  oxygen,  and  throw  off  carbonic  acid  ;  thus 
they  are  promotive  of  each  other's  health,  and  depend  the 
one  upon  the  other  for  their  very  existence. 

134.  Deconipositioii  of  Carbonic  Acid  hy  Solar  Light, 

De  Saussure  found  that  when  the  atmosphere  was  aug- 
mented from  tlie  natural  amount  of  carbonic  acid  in  it 
(being  about  ^Vo"  bulk)  to  -^^^  plants  thrived  more 

rapidly  in  the  sunshme  :  but  beyond  this  it  acted  dele- 
teriously.  In  the  shade,  however,  any  increase  over  the 
natural  quantity  proved  injurious  to  plants. 

As  early  as  the  middle  of  the  eighteenth  century, 
Charles  Bonnet  of  Geneva  established  the  fact,  as  he  sup- 
posed, that  the  green  portion  of  plants  under  the  action 
of  solar  light  decomposes  the  carbonic  acid  taken  into 
them  by  their  roots,  when  carried  to  their  leaves,  assimi- 
lating the  carbon  and  rejecting  the  oxygen.  This  was 
a  remarkable  approximation  to  the  truth  for  that  early 
period. 

Ingenhouz,  a  German  physician,  subsequently  demon- 
strated that  thic:,  Bmi'^.al  action  was  the  result  of  sun- 
light purely,  and  that  t  he  coloring  matter  of  the  plant 
had  nothing  to  do  with  it ;  that  the  sun  does  not  begin  to 
perform  this  function  until  it  is  some  distance  abnye  the 
8 


170 


CHEMISTHY  OF  PLANTS. 


horizon,  and  ceases  it  entirely  during  the  darkness  of  the 
night;  that  plants  shaded  by  high  buildings,  or  other 
plants,  do  not  perform  this  function,  and  hence,  instead  of 
purifying  the  air  of  the  noxious  carbonaceous  vapors, 
really  render  it  poisonous  around  our  dwellings  ;  that  all 
plants  corrupt  the  surrounding  air  during  the  night, 
while,  aided  by  sunlight,  they  purify  it  by  retaining  the 
carbon  and  emitting  only  oxygen. 

De  Saussure  established  by  experiment,  that  young 
peas  in  sunlight  would  endure  an  atmosphere  for  some 
days,  containing  50  per  cent,  of  carbonic  acid.  When 
increased  to  66  per  cent,  however,  they  soon  died.  When 
reduced  to  -^^  part  of  the  acid,  they  flourished  better  than 
in  pure  atmospheric  air,  increasing  11  grains  in  eight  or 
ten  days;  while  in  the  natural  atmosphere,  the  increase 
was  only  6  grains. 

He  also  found  that  the  foliage  of  plants  could  not  long 
exist  in  air  exposed  to  direct  sunlight,  bereft  of  carbonic 
acid.  This  was  done  by  covering  young  plants  in  a  bell- 
glass,  and  exposing  them  to  the  action  of  moist,  caustic 
lime,  which  would  rapidly  absorb  the  carbonic  acid.  The 
leaves  soon  turned  yellow,  and  dropped  off  in  two  or  three 
weeks.  In  the  dark,  however,  they  flourished  all  the 
better,  by  having  the  carbonic  acid  taken  up  by  the  lime. 

Boussingault  also  demonstrated  that  pure  carbonic 
acid  was  not  decomposed  by  the  leaves  of  plants  in 
sunlight,  as  when  mixed  with  oxygen,  nitrogen,  and 
hydrogen. 

From  experiments  by  De  Saussure,  and  later,  by  linger 
and  Knop,  it  has  been  proven  that  the  oxygen  exhaled  in 
sunlight  is  nearly  equal  in  volume  to  the  carbonic  acid 
absorbed.  As  the  free  oxygen  occupies  the  same  bulk 
as  the  carbonic  acid,  most  of  the  carbon  is  retained  by  the 
plant. 

The  amount  of  carbonic  acid  absorbed,  however,  is 


FIXATION  OF  CARBOX  IN  PLANTS. 


171 


much  greater  by  daylight,  than  that  exhaled  during  the 
night.  The  colza,  bean,  raspberry,  and  sunflower,  in  15  or 
20  minutes  of  direct  sunlight,  absorbed  as  much  carbonic 
acid  as  they  exhaled  during  a  whole  night. 

Corinwinder  also  found  that  a  colza  plant  took  up  in 
one  sunshiny  day  more  than  two  quarts  of  gas,  the  carbon 
of  which  was  retained. 

Boussingault  found  that  a  square  surface  of  oleander 
leaves  decomposed  in  one  horn  of  sunlight,  sixteen  times 
as  much  carbonic  acid  as  the  same  surface  of  leaves  exhaled 
in  the  dark  in  the  same  length  of  time. 

135.  Fixation  of  Carbon  in  Plants, 

It  is  believed  that  the  grains  of  chlorophyl  in  the 
stems  and  leaves  of  plants  has  an  intimate  relation  with 
the  fixation  of  carbon  from  the  carbonic  acid  of  the  atmo- 
sphere. Microscopic  observations  of  the  developments  of 
some  of  the  carbo-hydrates,  especially  starch,  which  begins 
its  organization  in  the  chlorophyl  grains,  as  well  as  some 
experiments  made  by  Gris,  in  the  withholding  iron  from 
plants,  have  led  to  this  conclusion.  This  chemist  found 
that  when  iron  was  withheld  from  plants,  the  leaf  would 
attain  a  certain  development,  but  chlorophyl  not  being 
formed,  the  plant  would  soon  die. 

Prof.  Johnson  also  states  that  experiments  show  that 
oxygen  is  given  off,  carbonic  acid  decomposed,  and  carbon 
fixed,  only  where  the  microscope  reveals  the  presence  of 
chlorophyl. 

The  unfolded  leaves  of  plants  imbibe  carbonic  acid 
and  decompose  it,  fixing  the  carbon  through  chlorophyl, 
the  oxygen  being  set  free.  This  process  transpires  only 
under  the  influence  of  sunlight,  which  produces  decom- 
position. The  carbo-hydrates  whicli  result  from  the 
carbon  thus  fixed,  are  believed  to  be  formed  in  the  chloro- 
phyl cells  of  the  leaf. 


172 


CHEMISTRY  OF  PLANTS. 


Carbon  is  also  fixed  in  the  plant  under  the  influence 
of  light,  as  first  discovered  by  Ingenliouz  as  early  as  1779. 

When  a  seed  germinates  in  the  absence  or  light,  it 
loses  its  weight  by  slow  oxidation  from  the  consumption 
of  carbon  and  hydrogen.  Boussingault  proved  this  in  an 
experiment  with  two  beans;  one  being  placed  in  dark- 
ness and  the  other  in  ordinary  light  for  26  days.  The 
gain  and  loss  of  dry  w^eight  of  carbon  is  thus  estimated: 


136.  Exhalation  of  Carbonic  Acid  in  Diffused  Light, 

It  was  early  demonstrated  by  De  Saussure  and  others 
that  carbonic  acid  is  exhaled  from  plants  during  nights 
and  cloudy  days,  in  the  absence  of  solar  light. 

Senncbier  found  that  the  oxygen  which  was  exhaled 
by  sunlight,  was  produced  by  the  decomposition  of  car- 
bonic acid,  while  the  carbon  was  appropriated  to  the 
plant,  and  it  is  believed  that  carbonic  acid  is  not  absorbed 
and  decomposed  by  the  plant  in  total  darkness,  but  only 
produced  in  and  exhaled  from  it. 

Either  oxygen  or  carbonic  acid  may  be  exhaled  from 
plants  in  preponderating  quantities,  of  cloudy  days  and 
in  diffused  light,  according  to  circumstances.  Corinwinder 
discovered  an  exhalation  of  carbonic  acid  in  this  diffused 
light  from  several  plants,  as  tobacco,  cabbage,  sunflower, 
etc. 

Under  similar  conditions  he  observed  the  evolution 
of  oxygen  from  the  lettuce,  pea,  violet,  and  fuchsia.  In 
one  experiment  the  bean  exhaled  neither  gas.  Plants 
when  quite  young  evolved  carbonic  acid  better  than 
when  old;  when  quite  old  they  ceased  it  altogether. 

In  later  investigations  in  1861,  Coi  in  winder  found 


Gain  in  light. 


LosB  in  darkness. 


Carbon . . . 
Hydrogen 
Oxygen  .  . 


0.1926 
0.0200, 
.0.1591 


0.1598 
0.0332 
0.1766 


SUPPT-Y  OF  CARBONIC  ACID. 


173 


lliat  buds  and  young  leaves  absorb  oxygen,  and  exhale 
carbonic  acid  even  in  bright,  sunshine.  He  also  found 
that  all  leaves  exhale  carbonic  acid  by  day  as  well  as  by 
night,  when  placed  in  the  diffused  light  of  a  room  Avhich 
is  illuminated  only  from  one  side.  A  plant  which  in  full 
light  yields  no  carbonic  acid  from  its  foliage,  immediately 
gives  off  this  gas  when  placed  in  such  an  apartment,  and 
ceases  to  do  it  when  removed  from  it. 

Garreau  in  1851,  and  Corinwinder  in  1858,  I'eviewed 
the  whole  subject  of  the  relation  of  carbonic  acid  tu 
plants,  confirming  former  conclusions,  and  adding  more 
facts  to  those  already  ascertained.  They  found  that  there 
are  constantly  going  on  in  tlie  plant  two  opposite  pro- 
cesses ;  the  first,  the  exhalation  of  carbonic  acid  and 
evolution  of  oxygen  ;  this  process  corresponding* to  the 
respiration  of  animals  ;  the  other  process  being  the  fixa- 
tion of  carbon  in  plants. 

The  absorption  of  oxygen  and  exhalation  of  carbonic 
acid  seem  to  be  independent  of  solar  light,  and  go  on 
during  every  hour  of  day  and  night.  But  although  car- 
bonic acid  is  constantly  produced  under  the  influence  of 
the  solar  rays,  the  absorption  of  carbonic  acid  and  exhala- 
tion of  oxygen  take  place  with  greater  rapidity,  so  that 
the  first  result  is  completely  masked  to  the  experimenter. 
The  preponderance  then  of  the  latter  process  over  the  for- 
mer is  all  that  we  can  estimate. 

187.  Supply  of  Carbonic  Acid, 
Although  carbonic  acid  forms  so  Fmall  a  part  of  the 
weight  of  the  atmosphere  (about  ^oIto')?  J^^j  estimated  in 
its  entire  height  in  the  air  surrounding  the  globe,  there  are 
in  round  numbers  3,400,000,000,000  tons;  amounting  to 
about  28  tons  for  every  acre  of  the  earth's  surface. 

Chavendier  estimated  that  an  acre  of  beech  forest  would 
consume  annually  1950  lbs.  of  carbon,  equal  to  3^  tons  of 


174 


CHEMISTRY  OF  PLANTS. 


gas.  Thi-s  would  in  about  eight  years  consume  all  the  car- 
bonic acid  of  the  atmosphere,  if  every  acre  of  vegetation 
destroyed  as  much,  and  there  were  no  processes  of  restora- 
tion going  on.  (How  Crops  Feed,  p.  47.) 

But  when  we  remember  that  not  more  than  one-fourth 
of  the  earth's  surface  is  land,  and  the  general  average  of 
consumption  must  be  much  below  that  of  a  thrifty  forest, 
as  Prof.  Johnson  says,  we  are  warranted  in  the  assumption 
that  there  is  now  existing  enough  for  one  hundred  years' 
growth  without  any  replenishing. 

But  then,  as  we  have  already  stated,  this  ingredient  of 
the  atmosphere  is  resupplied  as  fast  as  appropriated  to 
vegetation,  by  the  oxidation  of  carbon  from  decay  of  or- 
ganized bodies,  both  animal  and  vegetable,  the  combustion 
of  fuel,  and  the  respiration  of  animals. 

138.    CarhoiiiG  Acid  from  tJie  Soil, 

Although  it  is  belicA^ed  that  about  one-third  of  the  car- 
bon of  plants  is  supplied  them  through  the  roots  from  the 
soil,  yet  it  is  equally  true  that  some  plants  may  grow  to  a 
normal  standard  without  receiving  any  carbon  from  the 
soil. 

Boussingault  developed  full-sized  sunflowers  in  this 
w^ay,  which  received  no  carbon  from  the  soil  except  what 
the  seed  contained.  Prof.  S.  W.  Johnson  did  the  same 
with  buckwheat,  and  others  have  produced  perfect  plants 
of  maize  and  oats  in  weak  saline  solutions  without  car- 
bon. 

Recent  experiments  by  Hellriegel  have  led  him  to  infer 
that  the  atmospheric  supply  of  carbonic  acid  is  probably 
sufficient  for  the  jDroduction  of  a  maximum  crop  under  all 
circumstances,  as  an  artificial  supply  to  the  soil  had  no  eflect 
to  increase  the  crop.  We  think,  however,  that  this  needs 
fiirther  demonstration,  as  there  are  many  facts  which  tend 
to  prove  that  plants  receive  a  good  portion  of  carbon 


CHAXGES  IN  THE  VEGETABLE  TISSUES.  175 


through  their  roots  ;  not  the  least  of  which  is,  that  the  sap 
of  plants  is  little  else  than  carbonated  water. 

139.   Carbonic  Acid  cts  ci  Solvent. 

Carbonic  acid  does  not  only  furnish  food  directly  to 
plants,  but  is  one  of  the  best  solvents  in  nature  for  the  pre- 
paration of  other  insoluble  substances,  not  otherwise  capa- 
ble of  being  appropriated  as  plant-food.  In  union  with 
water  it  not  only  attacks  the  insoluble  phosj^hates  of  the 
soil  and  renders  them  soluble,  but  granite,  limestone,  and 
magnesia  rocks,  which  are  by  slow  processes  disintegrated 
and  crumbled  into  fine  powder,  and  made  available  food  for 
plants. 

By  uniting  with  the  ammonia  of  the  atmosphere,  and 
the  potash  and  soda  of  the  earth,  carbonic  acid  forms  three 
alkaline  carbonates,  all  of  which  have  the  power  of  dissolv- 
ing silica,  which  enters  very  largely  into  the  straw  of  the 
cereals  and  some  other  vegetable  organisms. 

The  three  minerals  of  which  granite  is  composed,  quartz^ 
feldspar,  and  mica,  all  contain  a  large  amount  of  silica,  and 
are  slowly  attacked  by  these  carbonates,  and  rendered  sol- 
uble, and  by  union  with  the  potash  made  available  as  plant- 
food. 

140.    Changes  in  the  Vegetable  Tissues. 

Lawes,  Gilbert,  and  Pugh  made  some  interesting  expe- 
riments to  estimate  the  changes  which  transpire  in  the 
vegetable  tissues.  They  found  that  the  atmospheric  air  in 
plants,  wdien  removed  from  sunlight,  had,  in  an  average  of 
three  experiments,  nitrogen,  74.08,  oxygen,  7.37,  and  car- 
bonic acid,  18.56  per  cent.  While  in  sunlight  it  had  of 
nitrogen,  33.4,  oxygen,  26.02,  and  carbonic  acid,  5.56  per 
cent.  Thus  at  night  the  air  of  plants  contained  41.04  more 
nitrogen  than  under  the  solar  rays,  18.65  less  of  oxygen, 
and  13.00  less  of  carbonic  acid. 

Admitting,  as  we  must,  that  the  atmospheric  air  freely 


.176 


CHEMISTRY  OF  PLANTS. 


penetrates  the  vegetable  tissues,  we  can  easily  perceive 
what  changes  are  going  on  in  them  day  and  night.  In 
sunlight  the  carbonic  acid  undergoes  decomposition,  the 
oxygen  being  set  free,  while  the  carbon  remains  to  form  the 
solid  constituents  of  the  plant.  In  darkness  the  oxygen 
of  the  air  in  the  plant  takes  carbon  from  the  vegetable  tis- 
sues, and  forms  carbonic  acid  with  comparative  rapidity, 
so  that  the  oxgen  is  reduced  from  its  normal  standard  21, 
down  to  7.37,  on  an  average,  and  in  one  of  the  experiments 
as  low  as  3.75  :  while  in  others  not  here  estimated  it  is  re- 
duced to  less  than  one  per  cent.  (How  Crops  Feed,  p.  46.) 

141.   Tahidar  View  of  the  delation  of  Atmospheric 
Ingredients  to  Plant  Life, 

The  following  tabular  view  of  the  relation  of  the  atmo- 
spheric ingredients  to  the  life  of  plants,  is  given  by  Prof. 
Johnson.  (How  Crops  Feed,  page  98.) 

ABSORBED  BY  PLANTS. 

Oxygen,  \>j  roots,  flowers,  ripening  fruit,  and  by  all  growing  parts. 
Carbonic  acid,  by  foliage  and  green  j^arts,  but  only  in  the  light. 
Ammonia,  as  carbonate,  by  foliage,  probably  at  all  times. 
Water,  as  liquid  through  the  roots. 

Nitrous  acid,  \  united  to  ammonia  and  dissolved  in  through  the 
Nitric  acid,    S  roots. 

i 


Ozone,        ,  ,  . 

'        \  uncertani. 
Marsh  gas, ) 

NOT  ABSOKBED  BY  PLANTS. 

Nitrogen. 
Water  in  vapor. 

Oxygen, )  foliage  and  green  parts,  but  only  in  the  light. 
Ozone,  ) 

EXHALED  BY  PLANTS. 

Marsh  gas  is  transferred  by  aquatic  plants  Y 
Water  as  mjyor,  from  surface  of  plants  at  all  times 
Carlonic  acid,  from  the  growing  parts  at  all  times. 


INOKGANIC  ELEMENTS  AND  THEIR  IMPORTANCE.  177 


CHAPTER  III. 

MINERAL  ELEMENTS  OF  PLANTS.— THOSE  DEEMED 
ACCIDENTAL.  THOSE  ABUNDANT  IN  SOILS. 

142.  Inorganic  Elements  and  their  Importance, 

The  mineral  or  inorganic  constituents  of  plants  are 
alumina,  manganese,  iodine,  iron,  silicium,  sulphur,  phos- 
phorus, chlorine,  potassium,  sodium,  calcium,  and  magne- 
sium. 

Of  these,  alumina,  manganese,  and  iodine,  are  deemed  to 
be  rather  accidental  than  essential ;  while  iron  and  silica 
are  so  abundant  in  nature  that  tliey  are  never  exhausted 
from  a  soil,  or  needed  as  a  fertilizer. 

None  of  these  inorganic  elements  are  capable  of  enter- 
ing the  structure  of  plants,  as  they  exist  in  soils  or  rocks 
in  a  solid  state,  however  minute  they  may  be  made  ;  and 
with  the  exception  of  sulphur,  are  rarely  found  in  an  un- 
combined  state,  but  most  generally  combined  with  oxy- 
gen, occasionally  with  one  another,  and  with  carbonic  acid. 

Metallic  oxides  exist  in  every  plant,  and  may  be  de- 
tected in  their  ashes  after  incineration,  and  the  organic 
acids  existing  in  the  juices  of  vegetables  are  generally 
combined  with  these  metallic  oxides,  or  the  inorganic 
bases. 

The  following,  among  other  considerations  which  might 
be  mentioned,  w^ill  show  the  importance  of  the  inorganic 
elements  to  plant-life : 

1.  On  whatever  soil  a  healthy  plant  is  grown  the 
quantity  and  quality  of  the  ash  is  nearly  the  same. 

2.  While  each  species  shows  about  the  same  quantity 
of  the  same  elements,  distinct  species  show  very  diiFerent 
results,  both  as  to  kind  and  quantity;  and  the  more  remote 


178 


CHEMISTRY  OF  PLAIS'TS. 


the  natural  affinity  of  the  species,  the  wider  the  differ- 
ence. 

3.  No  perfect  plant  can  be  produced  in  a  soil  where 
one  of  the  more  important  elements  is  absent,  as  phos- 
phorus, potassium,  sulphur,  calcium,  magnesium,  etc= 

4.  Soils  which  have  been  reduced  to  a  very  low  state 
of  fertility  by  constant  cropping,  and  carrying  off  their 
elements  in  the  crops,  have  been  at  once  restored  to  their 
original  fertility  by  a  reapplication  of  these  mineral  ele- 
ments. 

143.  Alumina^  AL^Og. 

Alumina  is  the  only  known  oxide  of  aluminum.  It  is 
isomorphous,  with  sesquioxide  of  iron,  and  so  intimately  as- 
sociated with  the  peroxide,  that  they,  together  with  silica, 
form  the  red  clay  hills  of  all  primary  regions. 

The  hydrate  of  alumina  combines  with  certain  kinds  of 
organic  matter  so  intimately  as  to  extract  their  coloring 
matters  and  thus  form  the  i^igments  which  are  termed 
lakes.  Thus  its  intimate  association  and  combination  with 
the  vegetable  matters  of  the  soil  have  important  offices  in 
agricultural  production. 

Alumina  combined  with  silica  forms  clay  which  con- 
stitutes the  basis  of  porcelain  and  earthenware.  This  is 
a  most  essential  ingredient  of  all  fertile  soils,  improving 
their  physical  qualities  and  holding  moisture  and  ammonia, 
with  other  salts,  as  food  for  plants. 

The  sulphate  of  aluminum  and  potassium  (common 
alum)  is  known  to  possess  fertilizing  powers;  and  possibly 
by  this  means  plants  are  furnished  with  the  small  amount 
of  alumina  which  exists  in  them. 

The  phosphates  of  alumina  occur  in  such  inappreciable 
quantities  in  most  clay  soils,  as  to  elude  the  common  pro- 
cesses of  analysis;  and  yet  they  are  believed  by  chemists  to 
constitute  a  trace  of  all  clay  soils.    Being  insoluble,  how- 


MANGANESE. 


179 


ev'er,  tliey  can  only  furnish  food  for  plants  after  changing 
their  form. 

Pure  alumina  is  nearly  white,  and  has  48.70  of  oxygen, 
and  53.30  of  the  metal  aluminum. 

This  metal  was  first  discovered  by  Sir  H.  Davy,  and 
occurs  in  a  pure  state  in  some  rare  minerals,  as  corundum, 
the  sapphire,  and  the  ruby. 

Although  alumina  forms  a  large  portion  of  the  ci'ust 
of  the  globe,  it  contributes  but  liftle  to  the  direct  nourish- 
ment of  plants.  It  performs,  however,  a  very  important 
agency  in  agriculture,  and  constitutes  an  essential  part  of 
all  productive  soils.  Hence  it  is  important  that  its  phys- 
ical and  chemical  qualities  should  be  well  understood  by 
the  agricultural  student. 

According  to  De  Saussure,  Sprengel,  and  the  older 
chemists,  alumina  is  found  in  small  quantities  in  straw  and 
grains  of  most  agricultural  plants.  In  the  ash  of  wheat, 
Sprengel  found  in  one  analysis  1.90  per  cent.  Modern 
chemists,  however,  ignore  it  as  not  essentiah 

144.  Manganese^  Mn. 

Manganese  is  found  generally  but  sparsely  in  all  soils, 
mostly  associated  with  iron,  which  it  resembles  in  many 
of  its  properties.  It  is  not,  however,  used  to  any  extent  in 
the  arts. 

Oxide  of  Manganese  is  found  in  most  plants  in  small 
quantities,  either  as  peroxide,  MnO,  MngO.,,  or  sesquioxide, 
MrioO.^.  The  former  is  the  black  manganese  of  commerce, 
called  by  mineralogists  pyroto^V^. 

The  salts  of  manganese  exist  in  much  less  quantities  in 
plants  than  iron,  and  as  neither  of  the  oxides  is  soluble, 
they  must  first  be  changed  into  other  and  more  soluble 
forms,  as  the  chloride,  cai'bonate,  and  sulphate. 

J.  A.  Vs'anklyn,  in  investigating  the  value  of  different 
leaves  for  tea,  found  that  beech  leaves  contained  so  much 


180 


CHEMISTRY  OF  PLANTS. 


rnanganese  as  to  cause  it  to  show  a  decided  green  color  in 
the  dry  state,  and  upon  treatment  with  ^vater  it  exhibited 
the  characteristic  red  solution  of  permanganate  of  potash. 
It  may  thus  be  essential  to  certain  trees  and  plants,  as  the 
beech,  and  aid  in  giving  fragrance  to  tlie  tea;  but  in  com- 
mon agricultural  plants  it  is  not  deemed  an  essential  ingre- 
dient. 

It  has  lately  been  ascertained  also,  that  beech-nuts  con- 
tain a  large  percentage  of  manganese,  although  the  soil  in 
which  they  are  grown  may  exhibit  no  appreciable  trace  of 
this  metal. 

145.  Iodine^  I. 

Iodine  exists  in  sea  water  in  small  quantities  as  an 
iodide  of  sodium.  It  is  poisonous  both  to  animals  and 
plants. 

It  has  been  found  as  a  constituent  in  the  Fucus  lami- 
naria,  and  other  marine  plants,  but  has  never  been  detected 
in  crops  usually  raised  for  food. 

It  is  slightly  soluble  in  water,  and  affords  a  striking 
test  for  starch,  by  the  beautiful  blue  color  it  imparts  to 
this  substance  when  brought  in  contact  with  it. 

Iodide  of  potassium  has  been  applied  to  certain  plants, 
causing  them  to  thrive.  It  is,  however,  of  no  special  inter- 
est to  the  agriculturist,  although  it  may  be  true  that  cer- 
tain marine  j^lants  cannot  exist  without  it. 

146.  /ro/?.,  Fe. 

Iron  is  known  to  be  of  great  importance  to  plant-life, 
although  it  is  found  in  them  in  very  small  quantities.  The 
peroxide,  Fe^O.,  is  the  form  in  which  it  generally  exists  in 
plants. 

It  occurs  abundantly  in  nature,  more  so  than  any  other 
simple  element  except  siliciuni  and  aluminum.  As  indi- 
cated by  the  table,  it  has  30.66  per  cent,  of  oxygen,  and 
is  insoluble  except  in  water  containing  acid  in  solution. 


181 


It  has  the  power  of  absorbing  ammonia  from  the  atmo- 
sphere, as  well  as  from  soils,  when  deposited  in  fertilizers, 
or  by  rain  water,  and  thus  retain  it  for  the  benefit  of  plants. 

In  iron  soils  abounding  in  humus,  this  oxide  is  de- 
prived of  one-third  of  its  oxygen  by  the  carbon  of  the 
decaying  vegetable  matter,  and  thrown  back  into  a  pro- 
toxide, which,  being  made  soluble  by  the  acids  it  comes  in 
contact  with,  is  taken  up  by  plants  and  proves  deleterious 
to  them. 

A  good  practical  suggestion  may  here  be  made  ;  red 
irony  soils  should  be  stirred  as  frequently  as  possible,  so 
that  the  oxygen  of  the  air  may  unite  wiili  the  bLack  oxide, 
and  prevent  its  deleterious  elFects  upon  the  growth  of 
plants. 

The  tendency  of  the  black  oxide  is  to  unite  with  moi'e 
oxygen  and  form  the  red  oxide.  This  is  constantly  tran- 
spiring in  chalybeate  waters.  When  they  first  rise  they  are 
tinctured  witli  the  protoxide,  but  upon  exposure  to  air  they 
change,  and  the  stream  is  found  lined  with  a  reddish  sedi- 
ment of  insoluble  peroxide. 

Both  of  these  oxides  are  insoluble  except  in  water 
containing  acids  in  solution.  The  black  oxide  is  much 
more  soluble,  however,  in  the  same  weight  of  acid,  and  in 
boggy  lands  often  proves  injurious  to  vegetation. 

Carbonate  of  iron  is  another  form  which  exists  in  our 
soils,  especially  as  bog  iron  ore,  in  low  marshy  places. 
Being  wholly  insoluble  in  water  as  a  carbonate,  it  cannot 
as  such  prove  deleterious  to  plants,  but  is  first  converted 
into  a  peroxide,  and  then  back  into  a  jjrotoxide,  which  is 
very  soluble,  and  easily  taken  up  by  plants. 

As  iron  is  a  constant  constituent  of  all  plants  (though 
ofttimesin  mere  traces),  it  must  have  some  important  office 
to  perform  in  the  v(>getable  organism,  as  it  has  in  the 
animal,  where  we  know  without  it  the  blood  corpuscles 
could  never  be  formed,  and  death  would  soon  ensue  from 


182 


CHEMISTRY  OF  PLANTS. 


anemia.  Liebig  thinks  that  the  action  of  iron  is  so  im- 
portant to  the  function  of  jDlants,  that  the  absence  of  it 
would  endanger  their  existence. 

As  iron  is  a  necessary  constituent  of  the  food  of  ani- 
mals, they  must  die  without  it  in  their  food.  Hence,  as 
men  live  and  thrive  on  vegetable  diet,  it  is  inferable  that 
vegetables  intended  for  nutritious  food  would  have  iron  in 
them. 

Prince  Salm-Hostmar  planted  grass  and  colza  in  a  soil 
destitute  of  iron,  and  they  became  chlorotic;  but  when  iron 
was  put  in  the  soil  the  chlorosis  disappeared.  In  1849 
Eusebe  Gris  first  considered  chlorosis  of  the  leaves  due  to 
a  want  of  iron. 

M.  Boussingault  has  recently  shown  that  the  white 
blood  of  the  invertebrates  has  almost  as  much  iron  as 
red  blood ;  and  plants  destitute  of  green  coloring  matter, 
as  mushrooms,  have  as  much  as  those  which  are  colored. 

147.  Silica,  Si2O=60. 

Silica  occurs  as  rock  crystal,  or  in  massive  quartz. 
When  pure  it  is  perfectly  transparent  and  colorless,  ap- 
proaching in  hardness  the  precious  stones. 

Native  Silica  is  insoluble  in  water,  and  in  all  the  acids 
except  the  hydrofluoric.  It  has  the  power,  however,  when 
finely  divided,  of  uniting  with  bases.  Common  glass,  and 
other  artificial  forms  of  silica,  are  much  more  easily  acted 
upon  by  solvents  than  the  native  crystals. 

If  an  excess  of  hydrochloric  acid  be  added  to  a  dilute 
solution  of  an  alkaline  silicate,  the  silica  is  dissolved.  A 
solution  of  hydrate  of  silica  may  be  thus  obtained,  con- 
taining five  per  cent,  of  silica  in  cold  water.  This  may 
be  concentrated  up  to  14  per  cent,  by  boiling  down  in  a 
flask. 

There  are  two  forms  of  hydrate  of  silico,  one  of  which, 
very  white  and  light,  occurs  naturally  and  abundantly  in 


SILICA. 


383 


beds  at  the  base  of  the  chalk  formation.  This  forms  sili- 
cate of  calcium  when  united  with  slaked  lime. 

All  spring  and  river  waters  contain  traces  of  soluble 
silica,  as  tineiy  divided  sand  is  dissolved  by  the  alkaline 
carbonates.  The  silica  is  deposited  in  the  insoluble  form 
upon  evaporation.  Where  the  water  is  of  high  tempera- 
ture, as  the  boiling  springs  of  Iceland,  the  dissolved  silica 
occurs  in  large  quantities,  as  is  seen  deposited  in  petrifac- 
tions exposed  to  the  stream. 

A  class  of  minerals  called  zeolites,  also  contains  silica 
in  soluble  forms,  as  hydrated  siliceous  compounds. 

Thus  we  see  that  processes  are  constantly  going  ou 
in  nature  to  prepare  this  hard  and  insoluble  mineral, 
which  occurs  so  lai'gely  in  the  cereals  and  other  agricul- 
tural plants  to  be  assimilated  by  them. 

Xotwithstanding  recent  experiments  in  water  culture 
in  Germany  seem  to  indicate  that  silica  is  not  essential 
as  a  constituent  of  plant  food,  yet  we  cannot  believe  that 
a  substance  enterinsj  so  lars^elv  and  constantlv  into  aori- 
cultural  plants  could  be  merely  acci*lental.  Thus,  as  will 
be  seen  by  our  tables,  two-thirds  of  the  ash  of  wheat 
straw  is  composed  of  silica,  46.4  per  cent,  of  the  ash  of 
oat  grain,  and  27.2  of  barley;  while  the  ash  of  the  grain 
of  millet  with  the  husk,  is  more  than  one-half  silica. 

The  silicates  occur  abundantly  in  nature.  Clay,  fel- 
spar, mica,  hornblende,  and  a  large  number  of  other  min- 
erals, are  compounds  of  this  character.  Many  of  these 
are  double  silicates,  and  of  complex  composition. 

Silicic  acid  has  a  very  feeble  acid  character.  The 
ordinary  vegetable  acids,  as  the  acetic,  oxalic,  and  tartaric, 
separate  it  from  its  combinations  with  the  alkalies  ;  and 
the  same  purpose  is  effected  by  a  current  of  carbonic  acid, 
or  its  gradual  absorption  from  the  atmosphere. 


184 


CHEMISTRY  OF  PLANTS. 


CHAPTER  lY. 

OF  MINERAL  ELEMENTS  ESSENTIAL  TO  VEGETATION  AND 
NOT  ABUNDANT  IN  SOILS. 

148.   PhosrjlioTiis,  P=31. 

Phosphorus  was  discovered  by  Brandt  in  1669.  It 
never  occurs  in  nature  uncombined,  and  only  in  small 
proportions  as  a  phosphate  of  calcium,  in  the  primitive 
and  volcanic  rocks.  By  gradual  decay  it  passes  into  the 
soil,  where,  being  dissolved  by  carbonic  acid,  and  thus 
rendered  soluble,  it  accumulates  in  organic  matters,  being 
extracted  by  plants,  and  thus  becomes  sparsely  but  uni- 
versally diiiused  even  in  soils  which  have  none  in  their 
underlying  rocks. 

Phosphorus  is  a  colorless  waxy-looking  substance,  and 
becomes  hard  and  brittle  at  low  temperatures.  It  is  exter- 
nally inflammable,  takes  fire  in  the  open  air  at  a  tempera- 
ture but  little  above  its  freezing  point,  and  emits  white 
vapors  of  an  alliaceous  odor.  It  is  insoluble  in  water, 
slightly  soluble  in  ether,  oil  of  turpentine,  and  the  fixed  and 
essential  oils. 

This  important  element  seems  to  be  essential  to  the 
exercise  of  the  higher  functions  of  animals,  as  it  always 
exists  in  the  brain  and  nerves.  It  also  forms  the  principal 
part  of  the  earthy  constituent  of  their  bones. 

Phosphorus  furnishes  four  compounds  with  oxygen,  two 
of  them  anhydrous  : 

Phosphorus  anhydride,  P2O3=110. 

Phosphoric  anhydride,  P205=142. 

It  forms  also  three  oxidized  acids,  which  are  monobasic, 
dibasic,  and  tribasic,  in  proportion  as  the  oxygen  increases. 
Thus  we  have  : 


suLriiuR.  185 

Ilypophosphorous  acid  (monobasic),  IIPII.,Oi). 
Phosphorus  acid  (dibasic),  H.PHOs. 
Phosphoric  acid  (tribasic),  PI8PO4. 

When  the  oxide  of  phosphorus  represented  by  P2O5  is 
acted  on  by  water,  it  forms  phosphoric  acid,  a  most  essen- 
tial constituent  of  all  plants,  especially  of  the  seed,  and  the 
most  important  of  all  compounds  used  to  fertilize  soils. 

149.    SulpJiur,  S=32. 

Suljyhur  is  found,  native  or  uncombined,  in  amorphous 
masses,  or  in  transparent  yellow  crystals.  It  is  presented 
in  commerce  in  round  sticks,  called  roll  sulphur,  or  hrim- 
stone  ;  also  in  a  harsh  yellow  powder,  known  flowers  of 
s\dplim\  It  is  insoluble  in  water,  tasteless,  and  is  a  bad 
conductor  of  heat. 

Most  of  the  sulphur  used  in  this  country  is  obtained  from 
Sicily,  where  it  occurs,  uncombined,  in  a  blue  clay  forma- 
tion, stretching  for  a  number  of  miles  between  Mount  Etna 
and  the  southern  coast.  It  forms  many  compounds  in  na- 
ture, which  are  more  or  less  abundant,  as  the  sulphides 
of  iron,  copper,  lead,  and  zinc.  Iron  pyrites  (bisulphide 
of  iron)  is  extensively  used  in  the  manufacture  of  oil  of 
vitriol. 

Sulphur  exists  also  very  extensively  in  an  oxidized  con- 
dition as  sulphuric  acid  in  combination  with  various  earths; 
of  these,  the  sulphates  of  calcium,  magnesium,  barium,  and 
strontium  are  the  most  abundant. 

Sulphur  is  an  essential  ingredient  of  many  bodies  of 
organic  origin,  both  animal  and  vegetable  ;  it  is  a  neces- 
sary constituent  of  muscular  tissue  in  animals,  enters  into 
the  composition  of  several  volatile  oils,  and  is  always  found 
in  the  albumenoids. 

There  are  tvro  anhydrous  oxides  of  sulphur  :  sulphurous 
and  sulphuric.  The  acids  resulting  from  them  are  exten- 
sively used  in  the  arts.    The  sulphuric  acid  especially  is 


186 


CHEMISTRY  OF  PLANTS. 


important  to  the  agriculturist  in  many  ways  which  will  be 
treated  of  in  another  part  of  this  work. 

150.    Potassium,  K=39.1. 

Potassium  is  a  bluish  white  metal,  brittle,  having  a  cr3^s- 
talline  fracture  at  32°.  It  has  a  specific  gravity  of  0.865, 
being  light  enough  to  float  on  water. 

Oxygen  has  a  powerful  attraction  for  potassium,  which 
decomposes  nearly  all  the  gases  containing  it,  if  heated 
when  in  contact.  Three  well-defined  oxides  of  potassium 
are  formed  by  these  combinations,  the  most  important  of 
which  in  agriculture  is  potash,  K20=94.2. 

Hydrate  of  potash,  or  caustic  potash,  KHO,  is  prepared 
by  dissolving  pearlash,  an  impure  variety  of  carbonate  of 
potash,  in  ten  or  twelve  times  its  weight  of  water,  and  add- 
ing caustic  lime  equal  to  half  its  weight.  This  is  an  indis- 
pensable reagent  to  the  chemist,  and  has  been  used  in  cer- 
tain combinations  as  a  fertilizer. 

Potash  is  an  indispensable  constituent  of  all  fertile  soils, 
and  is  found  in  a  considerable  per  cent,  wherever  felspa- 
thic  and  micaceous  rocks  have  become  disintegated.  It  ex- 
ists largely  in  all  agricultural  plants,  as  will  be  seen  from 
the  tables  in  this  work. 

Chloride  of  potassium  and  magnesium  has  been  found 
in  extensive  beds  of  clay  in  the  neighborhood  of  Stassfurt, 
in  Prussia,  lying  immediately  above  a  bed  of  rock  salt  100 
feet  in  thickness.  It  is  used  extensively  as  a  fertilizer  in 
Europe,  and  is  now  combined  with  most  of  the  fertilizers 
for  cotton  and  tobacco  in  this  country.  This  bed  contains 
the  sulphates  and  chlorides  of  potassium,  sodium,  and  mag- 
nesium, and  is  believed  to  have  been  formed  by  the  drying 
up  of  an  inland  sea,  the  common  salt  crystallizing  out  first 
and  sinking  to  the  bottom.  Nearly  one-fourth  of  the  mine 
is  made  up  of  the  chloride  of  potassium. 


CALCIUM. 


187 


151.  Sodium^  !N'a=23. 

Sodium  has  a  bluish  white  color,  and  resembles  potas- 
sium in  most  of  its  qualities,  being  somewhat  more  volatile. 
It  forms  two  well-known  oxides  of  sodium,  common  soda 
and  the  peroxide  of  sodium  y  the  latter  contains  twice  as 
much  oxygen  as  the  former.  Besides  these,  a  blue  suboxide 
appears  also  to  exist. 

Sodium  occurs  in  several  minerals,  as  albite,  a  species 
of  felspar,  cryolite,  and  the  double  fluoride  of  sodium  and 
aluminum.  Borate  of  sodium  (common  borax),  is  also  a 
native  compound.  But  common  salt,  existing  in  extensive 
mines  and  in  sea  water,  is  the  great  source  from  which  the 
sodium  of  commerce  is  derived. 

Chloride  of  sodium,  as  such,  occurs  in  plants,  as  has  been 
noticed  under  chlorine.  Recent  experiments  in  water  cul- 
ture seem  to  indicate  that  soda  is  not  an  essential  consti- 
tuent of  plants. 

It  is  very  satisfactorily  jDroven  by  experiments  made  in 
1874  by  the  author,  in  flower-pots  containing  river  sand, 
out  of  which  all  soluble  matters  had  been  washed,  that 
soda  is  at  least  essential  to  the  cotton  plant.  The  pot 
containing  all  the  elements  except  sodium,  produced  a 
diminutive,  sickly  plant,  only  a  few  inches  high,  with  no 
branching  stems  or  any  forms  for  fruit,  much  less  the 
fruit  itself. 

152.  Calcium  J  Ca=40. 

Calcium  is  a  very  abundant  and  important  constituent 
of  soils  and  plants.  It  is  the  metallic  basis  of  lime,  from 
whence  it  derives  its  name,  calx^  lime.  It  is  found  in 
nature  in  combination  with  fluorine,  but  more  frequently 
as  a  carbonate  and  sulphate. 

Calcium  has  the  color  of  gold  alloyed  with  silver,  has 
an  intermediate  hardness  between  lead  and  gold,  and  melts 
at  a  red  heat.    Water  is  rapidly  decomposed  by  it,  hydro- 


188 


CHEMISTRY  OF  PLANTS. 


gen  being  evolved,  and  ?iydrate  of  lime  formed.  It  has 
only  one  oxide,  lime,  wliich  will  be  described  under  the 
head  of  special  fertilizers,  with  other  of  its  compounds 
deemed  useful  in  agriculture. 

It  is  a  very  essential  constituent  of  plants.  It  exists  in 
the  ash  of  some  of  the  grasses  from  10  to  12  per  cent.,  and 
in  clover  and  fodder  plants  from  30  to  60  per  cent.  It 
constitutes  10.5  per  cent,  of  the  ash  of  corn  stalks  and  37.9 
of  pea  vines.  In  cereal  grains  it  ranges  from  two  to  four 
per  cent. 

153.  Magnesium^  Mg=24. 

Magnesium  is  a  malleable,  ductile  metal,  having  the 
color  of  silver :  it  is  susceptible  of  a  high  polish,  but  is 
slowly  oxidizable  in  moist  air.  It  has  been  classed  with 
those  metals  the  oxides  of  which  form  the  alkaline  earths; 
but  is  now  deemed  by  chemists  to  be  more  analogous  to 
zinc  in  its  properties.  It  is  an  abundant  ingredient  of 
the  crust  of  the  earth,  and  occurs  in  large  quantities  as  a 
double  carbonate  with  calcium,  forming  dolomite  or  the 
magnesian  limestone. 

It  exists  in  all  agricultural  plants,  as  an  oxide  or  some 
of  its  compounds,  and  next  to  phosphoric  acid  and  potash 
is  the  most  abundant  constituent  of  seeds.  In  the  small 
grain  cereals  it  ranges  from  8  to  12  j^er  cent.,  and  in  Indian 
corn  runs  up  as  high  as  14.6  per  cent. 

154.    Chloriyie,  Cl=35.5. 

Chlorine  is  a  transparent  gas  of  a  greenish-yellow 
color.  It  is  much  heavier  than  air,  is  not  combustible, 
and  does  not  combine  directly  with  oxygen.  It  is  found 
abundantly  in  nature  in  combination  with  sodium,  with 
which  it  forms  our  common  table  salt. 

Chloride  of  sodium  is  the  most  abundant  saline  body 
found  in  sea  water  ;  and  many  beds  of  it  exist  in  various 


CHLOEINE. 


189 


parts  of  the  world.  Chloride  of  potassium  also  exists  in 
minute  quantities  in  the  waters  of  the  ocean,  and  has  been 
found  in  extensive  mines  at  Strassfurt,  Prussia. 

Chlorine  is  a  rare  constituent  both  of  plants  and  soils. 
As  it  is  found  as  chlorides  of  sodium  ai;id  calcium  in  vege- 
tation, it  is  probable  that  it  enters  plants  in  such  com- 
binations. And  as  green  leaves  under  the  influence  of 
the  sun  have  the  power  of  decomposing  common  salt,  it 
is  probable  that  whatever  of  chlorine  is  admitted  into 
plants  more  than  is  proper  to  their  nourishment  is  thus 
given  off.  The  same  may  be  true  of  other  chlorides,  as 
of  magnesium  and  potassium;  and  when  the  chlorine  is 
evolved  their  bases  may  be  retained  by  the  plant  as  appro- 
priate nourishment. 

The  chlorides  are  no  doubt  very  injurious  in  overdoses 
both  to  animal  and  vegetable  life  in  the  soil.  The  famous 
Dead  Sea  (Lake  Asphaltis)  of  the  East,  is  a  striking  me- 
mento of  this  fact,  as  vegetation  is  destroyed  on  its  shores 
and  for  miles  around.  It  was  a  custom  among  the  ancients 
when  they  wished  utterly  to  destroy  a  city,  to  plough  it 
up  and  sow  it  with  salt,  as  this  was  known  to  effectually 
kill  vegetation  for  many  years. 

Dr.  Kedzie,  of  the  Michigan  Agricultural  College,  says 
that  a  vigorous  sassafras  tree  on  the  college  grounds,  had 
inadvertently  poured  around  it,  a  quantity  of  strong  brine, 
which  formed  near  by,  a  stagnant  pool.  The  salt  was 
absorbed,  unchanged,  by  the  roots  in  immense  quantities 
which,  entering  the  circulation,  left  a  white  crystalline 
deposit  on  the  surface  of  the  leaves.  The  tree  withered 
and  died  in  a  short  time. 


190 


CHEMISTRY  OF  PLANTS. 


CHAPTER  V. 

PROXIMATE  ORGANIC  PRINCIPLES. — ALBUMINOIDS. 

•      155.  Proximate  Principles  of  Plants, 

The  proximate  organic  principles  of  plants  are  certain 
organisms  existing  within  them  composed  of  two  or 
more  of  the  four  organic  elements.  A  few  of  them  have 
also  sulphur  and  phosphorus  in  minute  proportions. 

Similar  compounds  exist  in  the  animal  structure,  but 
blinder  very  different  arrangements,  although  the  chemical 
constituents  are  very  near  the  same. 

These  principles  may  be  divided  into  albuminoids, 
carbo-hydrates,  vegetable  acids,  vegetable  oils,  alkaloids, 
and  coloring  matters. 

Water,  in  one  sense,  enters  into  vegetable  and  animal 
structure  as  an  organic  compound,  but  as  it  exists  abun- 
dantly in  nature  outside  of  organic  matter,  it  cannot  pro- 
perly be  classed  with  them. 

The  proximate  principles  of  plants  are  very  numerous. 
Hundreds  are  already  known  to  chemists  :  only  a  few,  how- 
ever, constitute  the  bulk  of  plants. 

Many  plants  contain  some  organic  principle  peculiar  to 
themselves,  in  the  form  of  oils,  acids,  bitter  principles, 
resins,  coloring  matters,  etc.  Thus  we  have  nicotine  from 
tobacco,  thein  from  tea  and  coffee,  quinia  from  the  cin- 
chona tree,  and  salacin  from  the  willow.  In  the  orange  arc 
found  three  different  oils  :  one  in  the  flowers,  one  in  the 
leaves,  and  another  in  the  rind  of  the  fruit. 

We  shall  only  treat  of  those  substances  which  are 
deemed  to  be  of  interest  to  the  agricultural  student. 

156.  A  Ihitmin  o  ids. 
The  Albuminoids  differ  from  all  other  proximate  prin- 


ALBUMEN. 


191 


ciples  in  having  all  the  organic  elements  existing  in  them 
with  minute  traces  of  sulphur,  and  in  some  cases  phos- 
phorus. 

The  albuminoids  are  called  protein  bodies,  from  a  notion 
of  Mulder  that  they  were  composed  of  various  hypothetical 
compounds  of  sulphur  and  phosphorus,  with  a  common  in- 
gredient which  he  termed  lyrotein.  Others  supposed  that 
they  were  identical  in  composition,  only  the  atoms  were 
arranged  differently,  as  in  cellulose  and  starch. 

While  the  arrangement  of  these  bodies  cannot  be  pro- 
perly accounted  for,  they  are  sufficiently  distinct  in  com- 
position to  be  readily  distinguishable  by  analysis,  and  yet 
their  differences  cannot  be  deemed  essentiaL 

There  are  three  albuminoids  existing  in  animal  and 
vegetable  substances  properly  distinguishable  from  each 
other,  though  very  nearly  related,  viz.  albumen,  fibrin,  and 
casein. 

Others  have  been  mentioned,  as  gliitine  and  legumine. 
The  former  was  described  by  Dumus  and  Cahours  as  a  pul- 
taceous  substance  resulting  from  crude  gluten,  which  Bous- 
singault,  however,  considered  a  compound  substance  con- 
sisting of  fibrin  and  casein,  with  a  little  starch  and  fat. 
JLegumine  exists  in  the  pod-bearing  plants,  and  though  de- 
scribed by  some  of  the  early  chemists  as  a  distinct  albu- 
minoid, is  now  classed  with  casein. 

157.  Albumen, 

Vegetable  albumen  exists  in  its  purest  form  in  the  white 
of  an  egg.  It  is  a  peculiar  thick,  glairy  substance,  has 
neither  color,  taste,  nor  smell,  is  insoluble  in  water  or 
alcohol;  but  dissolves  in  vinegar,  caustic  potash,  and  soda. 
It  exists  sparingly  in  the  seeds  of  plants,  but  occurs  large 
ly  in  the  fresh  juices  of  many  plants,  as  cabbage  leaves, 
turnips,  etc.  The  albumen  is  readily  separated  from  the 
juices  of  these  plants,  by  being  heated. 

If  the  water  which  remains  after  gluten  is  prepared 


192 


CHEMISTRY  OF  PLAXTS. 


from  wheat,  is  heated,  white  films  or  particles  of  albumen 
will  separate,  which  may  be  easily  collected. 

The  stench  emitted  by  the  putrefaction  of  the  albumen 
of  eggs,  is  owing  to  the  escaping  sulphuretted  hydrogen 
gas;  and  it  is  this  in  cooked  eggs  which  possesses  the  qual- 
ity of  blackening  silver  and  other  metals. 

Albumen  also  exists  in  the  muscles,  bones,  and  nerves 
of  animals. 

158.  Casein, 

Casein  is  the  purified  curd  of  milk,  and  the  basis  of 
cheese.  It  is  held  in  solution  in  milk,  and  constitutes  its 
most  nourishing  portions.  It  exists  dissolved  to  the  ex- 
tent of  3  to  6  per  cent,  of  fresh  milk,  is  not  coagulated  by 
heat  like  albumen,  but  by  acids  and  rennet  (the  membrane 
of  a  calf's  stomach);  also  with  salts  of  magnesia  and  lime, 
when  heated  to  boiling. 

When  it  stands  for  some  time  the  casein  of  milk  coagu- 
lates spontaneously.  It  has  recently  been  detected  in  the 
brain  of  animals. 

Vegetable  casein  is  found  in  wheat,  and  largely  in  le- 
guminous plants,  (17  to  19  per  cent.).  It  closely  resembles 
milk  casein,  in  all  respects. 

Those  foods  are  always  the  most  nutritive  w^hich  con- 
tain the  most  casein.  It  may  be  considered  as  the  stand- 
ard of  food,  furnishing  all  that  is  essential  to  the  growth 
and  nutrition  of  animals. 

159.  Fibrin, 

Fibrin  occurs  in  a  state  of  solution  in  the  blood  of  ani- 
mals, and  with  albumen,  forms  the  basis  of  muscle. 

When  blood  cools,  it  coagulates  spontaneously,  separat- 
ing from  the  watery  part  or  serum.  The  white,  stringy 
particles  of  this  coagulum,  which  adhere  together  and 
form  a  network,  is  pure  fibrin.  When  w^ashed  in  water 
the  red  coloring  matter  disappears,  leaving  W'hite  masses 
of  fibrin.    It  is  quite  flexible  and  elastic  when  moist. 


COMPOSITION  OF  ALBUMINOIDS. 


193 


When  dried  it  loses  about  30  per  cent,  of  water,  and  be- 
comes horny,  brittle,  and  semi-transparent.  It  is  perfectly 
insoluble  in  cold  water.  When  burned,  a  strong  odor  of 
sulphuretted  hydrogen  gas  escapes,  leaving  considerable 
ash. 

Vegetable  fibrin  is  found  in  the  seeds  of  the  cereals, 
accompanied  with  starch.  It  has  no  fibrous  structure  lil^e 
that  of  animals,  but  forms  when  dry,  a  tough  horny  sub- 
stance. 

160.  Other  Isfitrogenous  Compounds, 

Aleurone  is  the  name  given  by  Hartig  to  organized 
granules  of  plants  which  are  a  mixture  of  the  difierent 
albuminoids,  ablumen,  casein,  and  fibrin,  the  two  latter 
largely  predominating.  These  grains  sometimes  assume 
the  form  of  crystals,  and  are  called  crystalloid  aleurone.  It 
is  found  as  cubes  in  the  outer  part  of  the  potato  tuber. 
It  is  also  found  abundantly  in  the  Brazil  nut,  according 
to  Maschke,  as  a  compound  of  casein  with  an  unknown 
acid. 

Two  other  albuminoids  have  been  found  in  crude  wheat 
gluten;  gliadin  or  vegetable  glue,  which  is  very  soluble 
in  water  and  alcohol  ;  and  miieidin^  insoluble  in  water, 
and  sparsely  soluble  in  alcohol.  It  is  found  in  rye 
grain. 

Ceraline  a  new  principle  found  in  wheat  by  the  Messrs. 
Deveaux,  consists  of  the  compact  layer  just  inside  the  bran, 
and  is  generally  removed  with  it  in  the  process  of  bolting. 
It  is  highly  nitrogenized,  containing  also  phosphoric  acid. 
This  principle  is  said  to  stimulate  digestion,  and  is  used  in 
the  treatment  of  dyspepsia  by  the  faculty  of  Paris.  The 
valuable  properties  of  bran-meal  in  the  celebrated  Graham 
bread  are  thus  accounted  for  in  the  treatment  of  such  cases. 

161.  Composition  of  Albuminoids, 

The  following  table  arranged  by  Johnson  will  show  the 
9 


194 


CHEMISTRY  OF  PLANTS. 


composition  of  the  albuminoids,  animal  and  vegetable. 
He  did  not  include  phosphorus,  for  the  reason  that  its 
quantity,  if  not  its  very  presence,  is  deemed  uncertain. 
Voelcker  and  Norton  claimed  to  have  found  from  1.4  to 
2.3  per  cent,  of  phosphorus  in  casein,  and  other  chemists 
have  claimed  to  have  found  less  quantities  in  albumen  and 
fibrin.  (How  Crops  Grow,  p.  102.) 


Carbon.  Hydrogen.  Nitrogen.  Oxygen.  Sulphur. 


Vegetable  albumen  

...53.4.. 

..7.1.. 

..15.6.. 

..23.0.. 

..0.9 

...52.6.. 

..7.0.. 

..17.4.. 

..21.8.. 

1  2 

Wheat  fibrin  , 

...54.3.. 

..7.2.. 

..16.9.. 

.  .20.6. . 

1.0 

Vegetable  casein  

...50.5.. 

..6.8.. 

.  .18.0. . 

..24.2,. 

..0.5 

Gluten  casein  ^  , 

...51.0.. 

..6.7.. 

..16.1.. 

.  ,25.4. . 

..0.8 

Gliadin  >  Wheat  . . 

..52.6.. 

.  .7.0.. 

.,18.1.. 

..21.5.. 

.,0.8 

Mucidin  )  

...54.1.. 

..6.9.. 

..16.6.. 

,,21.5.. 

.  .09 

From  this  it  will  appear  that  there  is  but  little  differ- 
ence between  animal  and  vegetable  albuminoids,  as  to 
their  composition.    The  average  is  as  follows: 

Carbon.  Hydrogen.  Nitrogen.  Oxygen.  Sulphur. 

Animal  53.45. . .  .7.10. . .  .16.15. . ,  .22.05. . .  .1.22 

Vegetable  52.65. , ,  .6.95. , ,  .16.88. , .  .22,70. . .  .0.82 

162.  Albuminoids  in  Crops. 

As  it  is  a  very  difficult  and  uncertain  process  to  sepa- 
rate the  albuminoids  from  the  other  organic  principles, 
some  chemists  have  adopted  the  plan  of  simply  estimating 
their  amount  by  the  content  of  nitrogen  found  in  the  plant. 
This  is  near  enough  for  all  practical  purposes.  As  the 
albuminoids  contain  on  an  average  about  16  per  cent,  of 
nitrogen,  and  all  the  nitrogen  of  plants  exists  in  the  albu- 
minoids, it  is  easy  to  calculate  their  amount  when  the  per- 
centage of  nitrogen  is  known. 

From  the  table  given  by  Professors  Wolf  and  Knop, 


ALBUMINOIDS  IN  CROPS.  195 

we  select  the  most  interesting  agricultural  plants,  and 
parts  of  plants,  as  to  their  content  of  albuminoids  : 

Average  of  the  grasses   9.5 

Peas  in  blossom  14.3 

Lucerne       "   14.4 

Red  clover  "   13.4 

Rice,  grain  7.5 

Wheat  "   13.0 

Oats      "   12.0 

Maize     "   10.0 

Millet    "   14.5 

Buckwheat,  grain  9.0 

Peas  "   22.4 

Field  Beans    "  25.5 

Acorns  5.0 

Corn  fodder  (green)   1.0 

Pea  vines  "   3.2 

Wheat  straw  2.0 

Rye        "   1.5 

Barley   2.0 

Oat         "   2.5 

Pea         "   6.5 

Bean       "   10.2 

Corn-stalks  , . .  .3.0 

"    cobs  1.4 

Pea  hulls  8.1 

Bean  "   10.5 

Wheat  chatf  4.5 

Potato  (Irish)  2.0 

Turnip  (Ruta  Baga)  1.6 

Beet  1.1 

Pumpkin  1.3 


This  table  is  of  great  interest  to  the  agriculturist,  when 
it  is  remembered  that  an  article  is  nutritious  according  to 
the  amount  of  albuminoid  in  it.  All  of  these  substances 
were  thoroughly  air- dried,  except  those  marked  green.  It 
thus  appears  that  pea  vines  have  about  three  times  the 
nutriment  of  corn-fodder,  while  peas  themselves  have  more 


196 


CHEMISTRY  OF  PLANTS. 


than  twice  as  much  as  Indian  corn.  Our  corn-field  pea  is 
classed  as  a  bean,  which  is  still  more  nutritious  than  the 
pea. 


THE  CAEBO-HYDRATES. — CELLULOSE.  LIGNIN. — STARCH. 

AND  THE  GUMS. 


The  Carho-liydrates  are  composed  of  carbon,  hydrogen, 
and  oxygen,  without  nitrogen  ;  hence  their  name. 

They  have  been  divided  by  some  authors  into  the  Cel- 
lulose and  Pectose  groups.  We  think  the  following  a  more 
natural  division,  founded  upon  their  physical  as  well  as 
chemical  differences. 

Woody  Fibre^  Cellulose,  and  Lignin.  The  Starch 
Groiip^  Starch,  Inulin,  and  Dextrin.  The  Gums^  Arabin, 
Cerasin,  and  Vegetable  Mucilage.  The  Sugars^  Saccharose, 
Levulose,  Glucose,  and  Lactose.  The  Jellies^  Pectin,  Pec- 
tic  Acid,  and  Metapectic  acid. 


Cellulose  constitutes  the  skeleton  or  framework  of 
plants,  and  next  to  water  is  the  most  abundant  substance 
in  the  vegetable  world.  The  fibres  of  cotton,  flax,  and 
hemp  are  nearly  pure  cellulose  ;  in  fact,  nearly  every  part 
of  every  plant  contains  it,  as  it  forms  the  outer  coating  of 
all  the  cells.  Wood  fibre  is  constituted  of  long  cells  com- 
posed principally  of  cellulose  with  lignin. 

Cellulose  exists  in  various  vegetable  matters  when  air- 
dried,  in  the  following  proportions: 


CHAPTER  YI. 


163.  Carbo-hydrates, 


164.  Cellidose, 


Potato  tuber  . . . 
Wheat  kernel. 


Per  cent. 

...1.1 

...3.0 


STARCH.  197 
Per  cent. 

Maize  kernel  3.5 

Barley    "  8.0 

Oat         "  .....10.3 

Clover  hay...  .....34.0 

Maize  cobs  .38.0 

Oat  straw  40.0 

Wheat  straw  48.0 

Eye         "   54.0 


165.  Xiignin. 

It  is  now  well  ascertained  that  woody  fibre  is  composed 
of  cellulose,  already  described,  which  constitutes  the  skele- 
ton or  frame-work  of  this  fibre,  and  lignin^  which  is  much 
denser,  and  covers  it.  It  is  also  known  that  while  cellu- 
lose is  largely  digestible,  lignin  is  almost  entirely  indi- 
gestible. 

Lignin  is  more  solid  and  compact  than  cellulose,  and 
contains  more  carbon,  which  amounts  to  52.53  accord- 
ing to  Gay-Lussac  and  Thenard;  the  hydrogen  and  oxygen 
making  up  the  remaining  per  cent,  in  the  same  proportions 
found  in  water. 

166.  Starch, 

Starchy  next  to  cellulose,  is  the  most  abundant  of  all  the 
vegetable  principles,  being  found  in  all  classes  of  plants 
except  the  fungi.  It  is  a  tine  white  powder  without  taste 
or  smell,  and  is  insoluble  in  alcohol,  ether,  and  cold  water. 
It  exists  abundantly  in  wheat,  maize,  potato,  and  arrow- 
root ;  occurring  in  the  interior  of  vegetable  cells  in  the 
form  of  transparent  granules.  It  is  also  found  in  the  wood 
of  all  trees,  more  abundantly  during  the  autumnal  and 
winter  months.  The  sago-palm  (Metroxylon  Rumphii),  a 
tree  of  the  Malay  Islands,  produces  it  in  such  abundance 
that  one  tree  is  said  sometimes  to  yield  800  lbs. 

The  Irish  potato  (Solanum  tuberosum)  has  about  20  per 
cent,  of  starch,  which  may  be  separated  from  it  by  the  fol- 


198 


CHEMISTRY  OF  PLANTS. 


lowing  simple  process:  The  potatoes  are  reduced  to  a  pulp 
by  being  grated,  the  starch  grains  are  thus  released  from 
the  broken  cells.  The  pulp  being  placed  on  a  fine  sieve, 
is  agitated,  while  a  stream  of  water  is  teemed  upon  it, 
which  carries  through  a  milky  fluid,  containing  the  starch, 
while  the  cellulose  is  held  by  the  sieve.  The  milky  fluid 
is  poured  into  vessels,  and  allowed  to  settle,  when  the  water 
is  decanted,  leaving  the  starch,  w^hich  is  fit  for  use  when 
dried. 

The  corn  starch  of  commerce,  useful  as  a  bland  diet  for 
invalids,  is  prepared  from  maize,  by  dissolving  out  the  al- 
buminoids with  a  weak  solution  of  caustic  soda.  The  bran 
and  starch  are  then  separated  by  adding  water,  which 
causes  the  former  to  settle  ;  the  water  containing  the  starch 
is  poured  ofl*,  which  is  deposited  and  dried. 

Starch  is  a  very  important  ingredient  of  food  for  man 
and  domestic  animals,  and  is  said  to  be  dissolved  by 
their  saliva  at  blood  heat,  and  converted  into  sugar.  The 
liquids  of  the  large  intestine  perform  this  ofiice  much  more 
promptly.  (Johnson.) 

The  chemical  composition  of  starch  and  cellulose  are 
identical,  being  composed  as  follows  : 

Carbon  44.44 

Hydrogen  6.17 

Oxygen  49.39 

167.  Iiiulin, 

Inulin  was  first  obtained  by  Rose  from  a  decoction  of 
the  roots  of  inula  helenium,  or  elecampane,  and  is  very 
much  like  starch.  It  forms  the  greater  part  of  Jerusalem 
artichoke,  and  dahlia,  which  contain  no  starch.  It  is 
soluble  in  boiling  water.  It  seems  to  replace  starch  in  the 
natural  family  (compositse),  but  does  not  occur  in  grains 
as  starch,  but  in  the  liquid  form,  separating  from  the  juice 
after  standing  some  time  in  white  granular  particles.  The 


DEXTRIN. 


199 


dahlia  tuber,  according  to  Bouchardat,  contains  8  per  cent, 
of  this  substance. 

Inulin  maybe  converted  into  a  saccharine  matter  called 
levulose^  by  boiling  in  diluted  acids.  The  same  result  is 
accomplished  by  hot  water,  only  it  requires  a  much  longer 
time.  As  nutriment  it  has  about  the  same  value  as  starch. 
Its  composition  is  the  same  as  starch  and  cellulose. 

168.  -Dextrin, 

Dextrin  is  a  light  brown  substance,  found  by  Busse  in 
old  potato  tubers  and  unmatured  wheat  plants.  As  it  may 
be  made  artificially  from  starch,  and  has  not  been  found 
in  young  potatoes,  it  is  probable  that  it  results  in  old  ones 
from  the  transformation  of  starch. 

When  exposed  to  the  heat  of  an  oven  for  some  hours, 
starch  is  readily  converted  into  dextrin,  the  grains  swelling 
and  bursting  by  the  intense  heat.  It  has  been  found  in 
but  few  plants,  and  then  in  small  quantities.  Von  Bibra 
says  that  what  was  supposed  to  be  dextrin  in  bread  grains, 
by  the  early  chemists,  is  nothing  but  gum. 

When  biscuit  are  steamed,  the  crust  often  presents  a 
glazed  surface  ;  this  is  due  to  dextrin.  In  fact,  the  very 
process  of  baking  bread  changes  a  portion  of  the  starch 
into  this  substance,  amounting  often  to  ten  per  cent.  Under 
the  name  of  British  gum,  prepared  from  starch,  it  is  used 
extensively  in  the  arts,  particularly  in  printing  calicoes, 
being  cheaper  than  gum  arable,  and  answering  the  same 
purpose.  It  dissolves  readily  in  cold  water,  and  when  the 
solution  is  mixed  with  alcohol,  it  separates  in  white  flocks. 
Commercial  dextrin  is  changed  into  a  fine  purplish  color 
by  iodine  ;  but  pure  dextrin  is  not  affected  by  it. 

Dextrin  is  also  formed  from  starch  and  cellulose  by 
acids  and  fermentation.  It  is  composed  identically  as 
starch,  cellulose,  and  inulin. 


200 


CHEMISTRY  Or  PLANTS. 


169.    The  Gums. 

The  Gums  found  in  the  vegetable  kingdom  are  very 
extensive,  and  of  several  types.  One  is  found  in  gum 
arabic,  called  arabin  ^  one  in  gum  tragacanth  and  Bas- 
so ra  gum,  called  hassorin  /  that  in  the  plum  and  cherry, 
cerasin^  and  vegetable  mucilage  found  in  the  comfrey  and 
mallow  roots,  and  quince  and  flax  seeds.  There  are  others, 
but  these  constitute  the  principal  gums. 

Gum  arabic  leaves  about  3  per  cent,  of  mineral  matter, 
upon  incineration,  carbonates  of  lime  and  potash  ;  the  re- 
mainder being  arabic  acid.  This  latter  contains  100  parts, 
carbon  42.12,  hydrogen  6.41,  oxygen  51.47. 

The  gum  found  on  the  peach,  cherry,  and  plum  trees, 
is  a  mixture  of  arabin  and  cerasin.  Cold  water  will  dis- 
solve out  the  former  and  leave  the  latter  a  swollen  mass 
of  jelly,  which  is  composed  principally  of  metarabic  acid. 

JBassorin  has  much  similarity  to  vegetable  mucilage, 
if  not  identical  with  it.  It  is  insoluble  in  cold  water,  but 
forms  a  paste  with  it,  which  was  formerly  used  by  druggists 
for  labelling. 

Vegetable  mucilage  is  found  in  nearly  all  plants,  and 
may  be  produced  in  a  pure  state  by  soaking  flax  seed  in 
cold  water,  boiling  it,  and  then  strain  and  evaporate.  Al- 
cohol will  then  cause  it  to  separate  in  tenacious  threads. 
The  external  cells  of  the  flax  seed  contain  the  mucilage, 
Avhich  being  soaked  in  water,  swell  and  burst,  which  causes 
it  to  exude.  The  inner  bark  of  the  slippery  elm  (ulmus 
fulva),  so  extensively  used  in  the  South  as  a  mucilaginous 
drink  in  fever  cases,  also  contains  a  large  percentage  of  it. 

The  gums  are  converted  into  grape  sugar  (glucose)  by 
long  boiling  in  water.  They  are  generally  thought  to  be 
indigestible  and  devoid  of  nutritive  qualities.  We  satis- 
fied ourselves,  years  ago,  that  this  was  a  mistake,  as  we 
have  fed  children  upon  gum  arabic  exclusively  for  weeks, 


CAXE  SUGAR — SACCHAROSE. 


201 


both  as  food  and  medicine,  when  emaciated  with  summer 
complaint,  and  it  improved  them  in  flesh  and  strength. 
Eecently  Grouven  has  satisfactorily  demonstrated  that 
gum  arabic  is  digestible  by  animals. 

Yon  Bibra  gives  the  following  percentage  of  gum  in 
various  substances  air-dried. 


Wheat  kernel  4.50 

Wheat  flour  6.25 

Rye  flour  7.25 

Barley  flour  6.33 

Oatmeal  3.50 

Bice  flour  2.00 

Wheat  bran  8.85 

Bye  kernel  4.10 

Millet  flour  10.60 

Corn  meal  (maize)  3.05 

Buckwheat  flour  2.85 

Spelt  flour  2.48 


Such  a  large  percentage  of  soluble  gum  in  the  bread 
grains  is  doubtless  appropriated  at  least  in  part  to  the 
nourishment  of  animals,  being  possibly  first  converted  into 
sugar  by  acids  through  processes  peculiar  to  digestion. 


CHAPTER  YII. 

CARBO-HYDRATES,  CONTIXUED. — THE  SUGARS.  PECTIN. 

CHANGES  IN  PROXIMATE  PRINCIPLES. 

IVO.   Cane  Sugar — Saccharose, 

Sugar  occurs  in  several  forms,  the  principal  of  which 
are  cane  sugar,  fruit  sugar,  grape  sugar,  and  milk  sugar. 

Cane  Sugar  or  Saccharose^  so  called  because  it  was 
first  found  in  the  sugar  cane  (Acer  saccharinum),  con- 
stitutes the  sugar  of  commerce.  It  crystallizes  in  small 
rhombic  prisms,  and  when  pure  is  of  a  white  color.  Some 
9* 


202 


CHEMISTRY  OF  PLANTS. 


of  its  crystals  in  rock  candy  are  an  inch  or  more  in  length. 
It  is  also  found  in  the  beet,  sugar  maple,  sorghum,  maize, 
sweet  potato,  and  a  great  many  other  vegetables. 

The  following  table  will  show  the  average  percentage 
of  saccharose  in  the  juice  of  several  plants.  (How  Crops 
Grow,  p.  13.) 

Sugarcane  18     percent  Peligot. 

Sugar  beet  10       "    "    " 

Sorghum  OJ^        "   Goessman. 

Indian  corn,  in  tassel ..         "    "   Ludersdoff. 

Sugar-maple  sap  2^        "   Liebig. 

Red  maple  2^    " 

Cane  sugar  will  be  converted  into  equal  parts  of  grape 
and  fruit  sugar,  by  the  action  of  yeast  or  heated  diluted 
acid.  Its  composition  is  nearly  identical  with  that  of 
arable  acid;  viz.  in  100  parts,  carbon  42.11,  hydrogen 
6.43,  oxygen  51.46. 

171.   Grape  Sugar — Glucose, 

Grape  Sugar  or  Glucose^  exists  in  the  juices  of  many 
plants,  and  constitutes  the  crystals  which  form  in  honey; 
also  the  granular  sweet  masses  found  in  raisins  and  old 
dried  fruits.  It  crystallizes  in  cubes  or  square  tables.  It 
is  only  half  as  sweet  by  weight,  as  cane  and  fruit  sugar. 

Glucose  is  formed  from  starch  in  the  malting  of  grain, 
and  from  dextrin,  by  hot  diluted  acids.  The  prolonged 
action  of  these  acids,  it  is  said,  will  convert  cellulose  into 
it,  and  even  sawdust  by  this  process  will  form  an  impure 
syrup,  from  which  alcohol  may  be  produced. 

The  composition  of  grape  sugar  is  as  follows:  Carbon 
40.00,  hydrogen  6.6,  oxygen  53.33. 

Grape  sugar  occurs  in  a  number  of  trees  connected  with 
bitter  principles,  as  tannin  found  in  the  oak,  salacin  in  the 
willow  bark,  phloridzin  from  the  apple-tree  root,  and 
others  found  in  the  almond,  peach  kernel,  horse-chestnut, 


MILK  SUGAK. 


203 


etc.  These  bitter  principles  are  called  glucosides^  and 
some  of  them  are  nsed  as  medicines.  By  heating  with 
dilute  acids,  glucose  is  obtained  from  them. 

172.  Fruit  Sugar — Fructose, 

Fructose^  or  Fruit  Sugar ^  called  also  Levulose^  exists 
generally  in  combination  with  other  sugars,  in  honey, 
molasses,  and  most  acidulous  fruits.  It  is  equal  in  sweet- 
ness to  cane  sugar,  but  does  not  granulate  or  crystallize, 
being  generally  found  in  the  form  of  syrup.  Its  composi- 
tion in  100  parts  is  as  follows:  Carbon  40.00,  hydrogen 
6.67,  oxygen  53.33. 

The  composition  of  fructose  is  identical  with  that  of 
glucose. 

Crystallizable  sugar  has  been  made  from  molasses  by 
Dubrunfaut,  by  treating  with  a  concentrated  solution  of 
baryta.  When  the  carbonate  of  baryta  which  is  formed 
subsides,  the  saccharine  liquid  is  drawn  off,  and  submitted 
to  the  ordinary  processes  of  evaporation  and  crystallization. 

173.  3IUk  Sugar — Lactose. 

Milk  Sugar — Lactose^  crystallizes  in  four-sided  prisms, . 
and  has  less  sweetening  power  than  grape  sugar.  It  is  found 
only  in  the  milk  of  animals.  It  contains  exactly  the  ele- 
ments of  carbonic  acid  and  alcohol,  minus  one  atom  of  wa- 
ter ;  and  as  neither  of  tl^ese  compounds  exist  in  sugar,  they 
must  be  produced  by  a  different  arrangement  of  atoms,  and 
by  their  union  with  the  elements  of  water.  It  is  largely  pre- 
pared for  commerce  in  Switzerland,  from  the  whey  of  milk. 

The  composition  of  milk-sugar,  is  carbon  42.10,  hydro- 
gen, 6.40,  oxygen,  47.00. 

174.    Other  Saccharine  Substances. 
Other  sugars  are  found  in  plants  in  small  quantities, 


204 


CHEMISTRY  OF  PLANTS. 


but  are  not  deemed  of  sufficient  importance  to  require 
l^articular  notice.  Among  them,  Prof.  Johnson  mentions 
the  following  :  (How  Crops  Grow,  p.  78.) 

Mannite^  CeHuOe,  occurs  in  the  bark  of  several  species 
of  ash,  found  in  the  south  of  Europe  and  the  East,  as  the 
Fraxinus  ornus,  and  rotundifolia.  It  is  found  also  in  edible 
mushrooms,  and  the  sap  of  some  of  our  fruit  trees. 

Quercite^  CgHisOs,  found  in  the  acorn  in  colorless  crys- 
tals. My  cose  J  found  in  the  ergot  of  rye,  and  Finite^  which 
exudes  from  the  bark  of  a  Californian  and  Australian  pine. 

Honey,  sorghum,  syrup,  and  molasses,  generally  con- 
tain cane  sugar,  grape  sugar,  and  fruit  sugar.  The  reason 
why  saccharose  is  obtained  from  sorghum  with  difficulty, 
is  because  of  its  being  so  easily  changed  into  other  forms 
on  the  heating  of  its  solution.  The  fructose  in  molasses  pre- 
vents the  crystallization  of  the  other  forms  into  solid  sugar. 

The  honey  dew  which  we  find  on  the  leaves  of  the 
honeysuckle,  lime,  and  other  trees,  is  a  mixture  of  these 
three  different  sugars  with  gum. 

The  saccharine  matter  of  the  bread  grains,  supposed 
by  Vauquelin  and  other  early  chemists  to  be  crystallizable 
sugar,  is  also  composed  of  this  mixture,  as  has  been  recently 
established  by  Von  Bibra.  He  found  in  the  flour  of  dif- 
ferent grains,  the  following  quantities  of  sugar ;  some  par- 
taking of  the  character  of  saccharose,  and  others  of  glucose 


and  fructose: 

%  Per  Cent. 

Wheat  flour  2.33 

Wheat  bran  4.30 

Rye  flour  3.46 

Rye  bran  1.86 

Maize  meal  8.71 

Barley  meal  3.04 

Barley  bran  1.90 

Oat  meal  2.19 

Rice  0.39 

Buckwheat  meal  0.91 


PECTIN. 


205 


175.  Alcohol^  a  Product  of  Sugar, 

Alcohol^  so  extensively  used  in  the  arts,  is  a  product 
of  sugar,  when  mixed  with  water  and  a  ferment,  at  a  cer- 
tain temperature.  The  water  gives  fluidity — the  ferment, 
heat — which  begins  and  keeps  up  the  chemical  changes. 
In  this  process  the  sugar  disappears,  part  of  which  is  con- 
verted into  the  tissue  of  a  microscopic  plant,  and  a  part 
into  alcohol.    The  temperature  ranges  from  60  to  90^. 

Sugar  is  not  the  only  substance  which  produces  alcohol; 
as  rice,  potatoes,  and  other  starch  plants  produce  it  by  a 
similar  process  of  vinous  fermentation.  This  is  done,  how- 
ever, by  the  starch  being  first  converted  into  sugar  by 
spontaneous  action. 

Absolute  Alcohol^  Anhydrous^  has  the  following  for- 
mula:  C4H5O0.  It  combines  with  water  in  all  propor- 
tions ;  is  entirely  combustible,  burning  without  leaving 
any  residuum.  It  exists  in  all  fermented  wines  from  6  to 
25  per  cent.;  and  in  the  ardent  spirits  of  commerce,  from 
50  to  55  per  cent.  It  is  a  pure  difiiisible  stimulant,  with 
but  little,  if  any  nutritive  functions ;  a  good  medicine, 
when  properly  used,  and  a  most  seductive  and  fatal  poison. 
Restricted  to  its  uses  in  the  arts,  it  would  be  a  blessing  to 
mankind. 

176.  Pectin, 

Pectin,  vegetable  jelly,  forms  the  gelatinous  princi- 
ple of  certain  plants — was  discovered  by  M.  Braconnot, 
and  plays  a  very  important  part  in  the  2:)henomena  of 
vegetable  life.  Pure  pectin  is  quite  insipid,  and  when 
dried,  is  in  membranous  semi-transparent  pieces,  resem- 
bling isinglass.  M.  Fremy  supposes  that  pectin  results 
from  pectose,  a  substance  which  occurs  associated  with 
cellulose,  in  the  flesh  of  unripe  fruits,  and  the  roots  of 
beets,  turnips,  etc. 

\ 


206 


CHEMISTRY  OF  PLANTS. 


With  pectic  and  metapectic  acid,  pectin  constitutes  a 
a  class  of  carbo-hydrates  called  the  Pectose  group.  These 
bodies  are  found  in  pumpkins,  squashes,  many  berries, 
fruits,  and  root  crops.  They  constitute  an  imjDortant  part 
of  the  food  of  man  and  domestic  animals. 

Pectin  results  from  pectose  by  the  action  of  heat, 
acids,  and  ferments.  The  pectose  of  unripe  fruits  is 
changed  by  the  influence  of  acids  existing  in  them  into 
pectin.  The  viscid  gummy  substance  which  exudes  from 
baked  apples  or  pears  is  an  aqueous  solution  of  pectin. 

When  fruits  ferment,  pectin  is  changed  into  pectosic, 
and  subsequently  into  pectic  acid.  The  fruit  jellies  are 
composed  of  these  acids.  Pectosic  acid  is  soluble  in  boil- 
ing water,  but  pectic  acid  is  not.  Neither  of  them  is 
soluble  in  cold  water. 

When  fruit  jellies  are  kept  too  long,  and  decay,  the 
pectic  and  pectosic  acids  are  changed  into  another  form, 
metapectic  acid^  which  is  very  soluble  and  quite  sour.  The 
pectin  of  decayed  fruits  is  also  changed  into  it,  and  it 
has  also  been  found  in  beet  molasses.  This  acid  contains, 
according  to  formulae  of  Fremy,  CgHioO^  with  two  equiva- 
lents of  water. 

Pectin  has  been  prepared  by  Grouven  on  a  large  scale, 
from  beet-root  cake,  which  remains  after  the  sugar  has 
been  extracted  from  it.  This  is  effected  by  digesting 
with  dilute  chlorhydric  acid,  then  precipitating  and  wash- 
ing with  alcohol.  Pectin  and  pectic  acid  have  each  in  100 
parts,  as  follows : 


The  pectin  prepared  by  Grouven  is  almost  identical 
with  the  pectic  acid  analyzed  by  Fremy. 

It  is  believed  that  cellulose  passes  into  pectose  and 


Pectin. 
.40.67. 
..5.08. 
.54.25. 


Pectic  Acid. 


Carbon  . . 
Hydrogen 
Oxygen. . 


42.29 
.4.84 
52.87 


CHANGES  IN  PROXIMATE  PRIXCIPLES. 


207 


pectin  in  the  living  plant.  But  the  pectin  bodies  are  not 
convertible  into  sugar,  as  was  formerly  supposed. 

177.   Changes  in  Proximate  Principles, 

Constant  changes  are  transpiring  during  the  growth 
of  plants  in  the  different  proximate  principles.  Deherain 
says,  that  they  migrate  from  the  older  to  the  newly  formed 
leaves,  and  that  this  migration  is  associated  with  a  trans- 
formation of  glucose  into  cane  sugar  ;  that  when  the  seed 
is  formed  the  cane  sugar  is  converted  into  starch,  and 
the  albumen  into  gluten,  both  insoluble.  The  accumula- 
tion of  substances  in  the  seed,  and  the  conversion  of  solu- 
ble into  insoluble  principles  are  thus  accounted  for. 

He  demonstrates  this  by  taking  a  porous  vessel  filled 
with  distilled  water,  placed  in  another  vessel  containing  a 
solution  of  sulphate  of  copper  (bluestone).  The  salt  pene- 
trates into  the  inner  vessel  by  diflfusion.  To  which  if  a 
few  drops  of  baryta  water  be  added,  the  salt  is  precipi- 
tated, the  equilibrium  disturbed,  and  a  new  portion  of 
the  bluestone  diffuses  into  the  inner  vessel.  The  precipi- 
tation again  transpires  on  the  application  of  the  baryta 
water,  until  the  whole  of  the  sulphate  of  copper  has  passed 
and  becomes  precipitated. 

The  carbo-hydrates  are  remarkable  for  the  facility  with 
which  they  may  be  changed  into  each  other.  Thus  in  ger- 
mination, the  starch  of  the  seed  is  converted  into  dextrin 
and  glucose,  and  in  this  form  passes  into  the  embryo  to 
nourish  theplantlet.  Here,  again,  it  changes  into  cellulose 
and  starch.  In  the  sugar  beet  (which  is  destitute  of  starch, 
ut  contains  10  to  14  per  cent,  of  sugar),  in  certain  dis- 
eased conditions,  the  sugar  is  transformed  into  starch. 
The  cereals  sometimes  show  dextrin,  upon  analysis,  instead 
of  sugar  or  gum,  which  is  more  common. 

In  the  animal  economy,  similar  transformations  take 
place  during  the  process  of  digestion.    Cellulose,  starch, 


208 


CHEMISTRY  OF  PLANTS. 


dextrin,  and  the  gums,  are  converted  into  sugar  (glucose). 
Many  of  these  changes  which  take  place  in  nature  may  be 
produced  by  the  action  of  chemical  agents — as  heat,  acids, 
and  ferments.  Thus,  cellulose  and  starch  are  convertible 
into  dextrin  and  glucose,  by  boiling  in  dilute  acids.  Cot- 
ton or  paper  may  be  gradually  changed  into  sugar,  by 
strong  chlorhydric  acid  (spirit  of  salt.)  Cellulose  and 
starch  into  dextrin,  by  nitric  acid. 

A  singular  fact  noticed  by  Prof.  Johnson  is,  that  while 
these  changes  are  produced  by  physical  and  chemical  agen- 
cies in  one  direction,  they  can  only  be  accomplished  in  the 
reverse  manner,  under  the  influence  of  life.  Thus,  chem- 
istry may  reduce  a  higher  organism  to  a  lower  or  simpler 
one  ;  but  not  the  reverse.  In  nature,  however,  these  changes 
take  place  Avith  perfect  facility  either  way. 

All  of  the  carbo-hydrates  represented  by  cellulose  and 
starch  contain  12  atoms  of  carbon  united  with  20  to  24  of 
hydrogen  and  10  to  12  of  oxygen.  Their  change  then  into 
each  other  can  be  easily  effected  by  the  abstraction  or  ad- 
dition of  a  few  molecules  of  water. 

It  is  a  singular  fact  in  chemistry,  that  certain  bodies 
containing  precisely  the  same  elements,  are  very  different 
in  physical  qualities  and  appearance.  These  are  termed 
isomeric  bodies,  which  can  be  accounted  for  only  in  the 
fact,  that  the  same  quality  and  kinds  of  elements  are  ar- 
ranged in  different  proportions,  upon  the  same  principle 
that  an  architect  can  construct  out  of  the  same  material, 
very  different  kinds  of  structures.  Thus,  cellulose  and 
dextrin  being  isomerical  bodies,  must  have  the  carbon, 
oxygen,  and  hydrogen  of  which  they  are  composed,  very 
differently  arranged;  a  fact  which  is  clearly  inferable,  but 
which  chemistry  fails  to  reveal. 


MALIC  ACID. 


209 


CHAPTEE  VIII. 

VEGETABLE  ACIDS,  AND  VEGETABLE  OILS. 

178.    Vegetable  Acids. 

The  Vegetable  Acids  exist  in  great  numbers  in  all  classes 
of  plants.  They  are  better  characterized  than  the  other 
carbo-hydrates,  being  generally  obtained  in  the  crystallized 
state,  and  are  consequently,  more  nearly  assimilated  to  in- 
organic bodies.  They  have  also  the  general  characteristics 
of  mineral  acids,  forming  salts  by  uniting  with  bases,  etc. 
With  potash,  soda,  and  ammonia,  they  form  salts  soluble 
in  water,  and  with  other  bases,  they  form  salts  either  solu- 
ble or  insoluble,  according  to  the  kind  of  acid. 

Only  a  few  of  these  acids  are  of  special  interest  to  the 
agriculturist,  although  many  of  them  are  of  great  impor- 
tance in  the  economy  of  vegetation.  Among  these  we 
mention  acetic,  malic,  oxalic,  tartaric,  citric,  and  tannic 
acids. 

Acids,  in  a  general  sense,  are  sour  to  the  taste.  They 
are  better  characterized  as  substances  capable  of  uniting 
chemically  with  bases.  These  latter  are  the  opposite  of 
acids. 

When  acids  and  bases  unite,  they  are  termed  salts. 
Thus,  phosphate  of  lime  is  a  salt,  produced  by  the  chemi- 
cal union  of  phosphoric  acid  and  lime. 

179.  Malic  Acid. 

Malic  acid,  C^HgO^  is  found  in  apples,  strawberries, 
plums,  cherries,  and  other  fruits ;  but  always  in  a  combined 
condition.  Thus  in  tobacco  leaves  and  the  sugar  maple, 
it  occurs  as  a  malate  of  potash.  It  succeeds  tartaric  acid 
in  the  mountain  ash,  where  it  is  found  as  a  lime  salt  ;  the 


210 


CHEMISTRY  OF  PLANTS. 


tartaric  acid  losing  a  part  of  its  oxygen,  is  converted  into 
malic  acid. 

Malic  acid  never  occurs  pure  in  nature,  but  may  be 
found  in  the  shops  in  white  crystalline  masses,  being  ex- 
tremely soluble  as  well  as  sour. 

180.   Tartaric  Acid. 

Tartaric  acid^  C4H6O6,  occurs  abundantly  in  the  grape 
as  the  bi-tartrate  of  potash,  and  is  frequently  found  de- 
posited on  the  sides  of  wine  casks,  as  argol^  produced  by 
fermentation. 

When  purified,  this  substance  is  known  in  commerce 
as  Cremor  tartar ;  from  which  the  acid  may  be  easily 
extracted.  It  is  a  valuable  medicine,  and  the  acid  is  an 
ingredient  of  the  famous  Seidlitz  powders. 

181.  Citric  Acid. 

Citric  acid^  CgHgO^,  is  found  in  a  free  state  in  the 
juice  of  lemons,  oranges,  currants,  and  unripe  tomatoes. 
It  is  used  medicinally,  and  in  the  arts;  for  which  large 
quantities  are  extracted  from  the  lemon  and  the  lime.  It 
is  found  in  small  quantities  combined  with  lime  in  tobacco 
leaves,  artichokes,  beets,  coffee  berries,  and  the  bulbs  of 
onions. 

182.  Oxalic  Acid. 

Oxalic  acid^  C2H2O4,  2H2O,  exists  largely  in  the  wood 
sorrel,  as  a  binoxalate  of  potash.  It  exists  free  in  the 
bases  of  the  chick  pea,  and  is  found  in  many  other  plants, 
generally  in  a  state  of  combination.  It  may  be  seen  in 
the  shops  in  colorless  transparent  crystals,  resembling 
Epsom  salts  so  closely,  that  fatal  mistakes  have  been  made 
by  using  it  in  the  place  of  that  medicine,  as  it  is  a  rank 
poison. 

It  is  a  powerful  acid,  having  such  a  remarkable  affinity 
for  lime,  that  it  takes  it  even  from  sulphuric  acid.  Oxalate 


ACETIC  ACID. 


211 


of  lime  is  insoluble  in  water,  but  exists  dissolved  in  the 
cells  of  living  plants  while  in  a  growing  state. 

183.  Tannic  Acid. 

Tannic  acid  (tannin),  is  the  bitter  principle  found  in 
the  bark  of  the  oak,  hemlock,  sumach,  and  many  other 
plants.  It  is  used  extensively  in  the  arts  for  tanning 
leather,  having  the  remarkable  property  of  rendering  the 
hides  of  animals  insusceptible  of  putrefaction.  It  is  also 
a  useful  medicinal  astringent.  Sir  Humphry  Davy  found 
it  to  exist  in  the  Bombay  catechu  as  high  as  54.3  per 
cent.,  and  in  nut-galls  27.4. 

Dr.  SchifF  has  lately  arrived  at  the  conclusion,  that 
tannic  acid  is  an  ether  which  bears  the  same  relation  to 
gallic  acid,  that  ordinary  ether  does  to  alcohol.  The 
difference  between  tannic  and  gallic  acid  being  merely  in 
the  elements  of  water.  He  thinks  that  some  practical 
results  might  be  reached  with  regard  to  the  processes  of 
tannin,  if  some  method  could  be  discovered  by  which  these 
elements  could  be  displaced. 

Recently,  Dr.  McMurtie,  chemist  of  the  Department 
of  Agriculture,  has  analyzed  several  kinds  of  wood,  and 
found  in  the  heart  of  the  mesquite  (Algarobia  glaudulora), 
G.21  of  tannic  acid;  in  the  heart  of  the  Osage  orange 
(Madura  aurantica),  5.87  per  cent.  This  is  nearly  equal 
to  many  barks  used  in  tanning,  and  in  some  sections,  and 
especially  in  the  Southwest,  where  these  trees  grow  abun- 
dantly, they  may  be  successfully  introduced  in  this  branch 
of  industry. 

184.  Acetic  Acid, 

Acetic  acid^  HC2H3O2,  although  found  in  very  small 
quantities  in  the  juices  of  plants,  and  in  animal  fluids, 
is  of  such  importance  in  agriculture,  that  we  cannot  well 
omit  it  in  this  place.  It  results  as  vinegar  from  the  fer- 
mentation of  all  acid  fruits,  and  the  action  of  air  on  alco* 


212 


CHEMISTRY  OF  PLANTS. 


holic  liquors;  and  is  found  among  the  products  of  the 
destructive  distillation  of  organic  matters. 

It  is  well  known  that  when  sweet  wine  or  cider  is  ex- 
posed to  the  influence  of  the  atmosphere,  it  becomes  sour. 
This  change  is  owing  to  the  production  of  acetic  acid.  A 
mixture  of  sugar  and  water  will  produce  the  same  result. 

When  deprived  of  water  and  all  impurities,  acetic  acid 
contains,  according  to  analysis  of  Berzelius,  carbon  46.83  ; 
oxygen  46.82;  hydrogen  6.85. 

M.  Vauquelin  found  this  acid  in  the  sap  of  various  trees, 
and  in  the  chick  pea.  It  has  also  been  found  in  the  date, 
palm,  and  in  the  elderberry,  by  Scheele.  It  exists  in  many 
plants  as  acetates  of  lime  and  potassa,  and  with  other  bases. 

185.  Vinegar, 

Vinegar^  which  is  diluted  acetic  acid  with  some  im- 
purities, is  the  oldest  of  known  acids.  Reference  is  made 
to  its  chemical  action  on  nitre  [natron^  soda),  by  Solomon, 
showing  that  this  substance  would  destroy  its  sharpness 
and  neutralize  its  acid.  Mixed  in  the  proportion  of  one 
part  of  brown  sugar  to  seven  of  water,  with  a  little  yeast, 
in  a  cask,  the  bunghole  being  bound  with  a  thin  piece  of 
gauze  to  keep  out  the  insects,  and  exposed  to  the  atmo- 
sphere and  sun  for  several  weeks,  a  good  vinegar  for 
domestic  use  will  be  produced. 

The  German  method  of  acetification  will  produce  good 
vinegar  in  24  to  36  hours.  Take  one  part  of  alcohol, 
graded  at  80  per  cent.,  four  to  six  of  Avater,  with  one-thou- 
sandth of  honey  to  act  as  ferment.  This  mixture  must  be 
made  to  trickle  through  beech  shavings  previously  steeped 
in  vinegar,  and  placed  in  a  deep  oaken  tub.  This  vessel 
must  have  a  wooden  diaphragm  near  the  top,  perforated 
with  a  number  of  holes  loosely  filled  with  pack-thread  tied 
in  a  knot  to  prevent  its  falling  through.  The  liquid,  heated 
T5  to  83"^,  is  poured  on,  slowly  percolates  through  these 


PEUSSIC  ACID. 


213 


holes,  and  thus  becomes  minutely  divided,  and  exposed  to 
the  atmosphere.  There  must  be  also  holes  bored  in  the 
sides  of  the  tub,  for  the  admission  of  air.  To  make  strong 
vinegar,  the  liquid  should  be  passed  through  three  or  four 
times,  and  the  temperature  made  to  rise  to  100  and  104^ 
during  the  process.  The  contact  of  air  promotes  acetifica- 
tion,  which  consists  in  oxidation  of  the  alcohol. 

During  acetous  fermentation,  there  is  a  miscroscopic 
vegetable  growth  produced,  which  Pasteur  has  shown  to 
be  a  cryptogam  of  the  micraderma.  This  formation  is 
essential  to  the  progress  of  acetification.  It  is  doubtless 
similar  to  the  California  moss  (only  much  more  minute), 
which  was  used  so  extensively  in  making  beer  some  years 
since;  and  which  had  the  remarkable  properties  of  indefi- 
nite increase,  and  changing  water  in  which  it  was  placed 
into  a  palatable  acid  beverage  in  a  few  hours. 

186.  Prussic  Acid. 

There  are  a  number  of  other  acids  found  in  different 
plants,  but  of  minor  importance.  They  all  consist  of  defi- 
nite proportions  of  carbon,  hydrogen,  and  oxygen,  vary- 
ing but  little  in  composition,  with  one  exception,  viz. 
pimssic  {hydrocyanic)  acid.  It  contains  48  per  cent,  of 
hydrogen,  and  52  of  nitrogen,  without  a  particle  of 
oxygen,  and  is  the  most  powerful  poison  in  nature. 

It  is  found  in  the  bark  and  leaves  of  the  cherry  and 
peach,  as  well  as  in  their  kernels  and  fruit,  and  constitutes 
a  considerable  percentage  of  the  fruit  and  bark  of  the  wild 
cherry;  the  value  of  which,  as  a  medicine  in  lung-affections, 
is  supposed  to  depend  upon  this  acid.  Its  extreme  dilu- 
tion in  nature  renders  it  comparatively  harmless;  but 
even  here,  it  sometimes  produces  bad  effects.  One  single 
drop  of  Scheele's  concentrated  solution,  placed  upon  the 
tongue  of  a  cat,  will  produce  instant  death. 


214 


CHEMISTRY  OF  PLANTS. 


187.    Vegetable  Oils. 

TJie  Vegetable  Oils  are  divided  into  the  fatty  or  fixed 
oils,  and  essential  or  volatile  oils.  They  exist  to  a  consid- 
erable extent  in  many  plants.  Boussingault  extracted 
about  40  per  cent,  of  fatty  oil  from  the  colewort  seed. 
An  equal  quantity  is  found  in  the  kernel  of  the  cotton 
seed  after  being  deprived  of  its  hull.  Walnuts  contain 
from  40  to  70  per  cent.,  and  castor  beans  (Palma  Chrysti) 
as  high  as  62. 

The  common  bayberry  and  tallow  tree  of  Nicaragua 
have  their  fat  of  a  solid  consistence  at  ordinary  tempera- 
tures, which  has  to  be  extracted  by  heat.  This  is  an  ex- 
ception to  the  general  rule  ;  as  in  most,  if  not  all  other 
known  plants,  the  fats  exist  in  a  liquid  state. 

Oil  exists  in  the  vegetable  cells  in  minute  transparent 
globules.  The  grains  of  the  cereals,  especially  oats  and 
maize,  contain  it  in  appreciable  quantities  ;  and  this  is 
probably  the  reason  why  Indian  corn  is  considered  a  very 
heating  food  for  horses,  as  the  fat  of  vegetables  is  known 
to  be  productive  of  heat  in  the  animal  economy. 

188.    Volatile  Oils, 

Volatile  Oils  may  be  divided  into  three  classes :  those 
composed  entirely  of  carbon  and  hydrogen  ;  those  con- 
taining carbon,  hydrogen,  and  oxygen,  and  those  which 
have  an  addition  of  sulphur ;  one  of  them,  oil  of  mustard 
seed,  containing  nitrogen  also.  This  latter  class  consti- 
tute the  Essential  Oils^  which  exist  in  aromatic  plants. 

The  volatile  oils  generally  have  a  strong  aromatic 
odor,  and  leave  no  stain  or  grease-spot  on  white  paper. 
The  reverse  is  true  of  the  fatty  or  fixed  oils.  They  have 
certain  properties  in  common,  however,  as  insolubility  in 
water,  inflammability,  and  solubility  in  ether  and  alcohol. 


SAPONIFICATION. 


215 


Camphor  is  combined  with  essential  oils  in  many 
plants  of  the  labiate  family.  According  to  M.  Dumas, 
this  substance  contains  carbon,  79.2;  hydrogen,  10.4; 
oxygen,  10.4. 

Resin  and  wax  also  exist  in  solution  with  essential  oils, 
making  them  viscid  and  sticky.  The  balsams  which  exude 
from  certain  trees  are  nothing  but  solutions  of  resin  in 
essential  oils.  The  resin  remains  in  a  solid  state  when 
the  oils  are  evaporated.  The  resins  are  inodorous,  fusible, 
extremely  inflammable,  and  non-volatile. 


Tallow,  olive  oil,  and  butter  are  the  three  most  abun- 
dant fats  used  as  food  for  man.  They  consist  of  three 
substances,  viz.  stearin,  palmitin,  and  olein. 

Stearin  is  the  most  abundant,  and  is  the  principal  in- 
gredient of  tallow.  Palmitin  exists  largely  in  butter  and 
beeswax,  and  the  tallow  of  the  bay  berry.  It  is  named 
from  the  palm  oil  of  Africa,  of  which  it  is  a  principal 
ingredient.  Olein  is  the  liquid  part  of  fats  existing  abun- 
dantly in  all  oils.  It  is  obtained  by  bringing  olive  oil 
down  to  the  freezing  point ;  the  stearin  and  palmitin  be- 
come solid,  and  the  olein  is  poured  off  in  a  liquid  state. 

The  fat  formerly  called  Margarin  has  been  found  to 
be  a  mixture  of  stearin  and  palmitin. 

The  following  table  gives  the  centesimal  composition 
of  these  elementary  fats :  (How  Crops  Grow,  p.  92.) 


189.  Fixed  Oils, 


Carbon . . . 
Hydrogen 
Oxygen . . 


Stearin. 
..76.6. 
..12.4. 
..10.0. 


Palmitin. 
..75.9.. 
.  .12.2. . 


11.9 


Olein. 
.77.4 
.11.8 
.10.8 


190.  Saponification, 

When  the  fats  are  heated  with  strong  potash  or  soda- 
lye,  or  brought  under  the  influence  of  strong  acids,  or 


216 


CHEMISTEY  OF  PLANTS. 


heated  with  water  to  a  high  temperature — nearly  400^ — 
they  are  decomposed  ;  changed  into  fatty  acids  and  gly- 
cerine. These  acids,  stearic,  palmitic,  and  olein,  combine 
with  the  alkalies,  making  soap. 

Soft  soap  is  a  combination  of  potash  with  these  acids, 
mixed  with  water  and  glycerine.  Hard  soap  is  the  soda 
compound  with  these  acids,  free  of  glycerine. 

Stearin  candles,  so  called,  are  a  mixture  of  stearic  and 
palmitic  acid. 

Glycerine^  which  is  simultaneously  produced  with  the 
acids,  is  a  kind  of  liquid  sugar,  and  is  found  in  the  shops 
as  a  sweetish,  colorless  syrup. 

191.  Phosphor ized  Fats, 

Von  Bibra  first  discovered  the  existence  of  a  phospho- 
rized  fat  in  the  brain  and  spinal  cord  of  animals,  and  in 
the  yolk  of  eggs.  The  amount  of  phosphorus  in  this  ani- 
mal fat,  ranged  from  1.21  to  2.53  per  cent.  A  similar  fat 
was  found  by  Knop  to  exist  in  the  sugar  pea  and  other 
plants.  It  contained  in  100  parts,  carbon,  66.25  ;  hy- 
drogen, 9.52  ;  oxygen,  22.38  ;  phosphorus,  1.25. 

Topler  afterward  found  phosphorus  at  a  less  percentage 
in  the  oils  of  the  lupine,  horse-bean,  vetch,  horse-chestnut, 
wheat,  barley,  rye,  and  oats. 

Liebreich,  according  to  Hoppe  Seyler,  discovered,  in 
1864,  a  white  crystallized  body  in  the  brain,  which  he 
termed  JProtagon,  Its  composition  is  as  follows  :  carbon, 
67.2;  hydrogen,  11.6;  nitrogen,  2.7;  phosphorus,  1.5; 
oxygen,  17.0.  It  is  found  also  in  the  nerves  of  animals, 
and  in  the  oil  of  maize. 

192.  Fat  in  Vegetable  Products, 
The  oil  or  fat  of  plants  results  from  the  transforma- 
tion of  starch  and  cellulose,  as  starch  is  always  found  in  seeds 
not  matured,  which  disappear  and  give  place  to  oils  when 


THE  ALKALOIDS. 


217 


matured.  When  there  is  a  small  percentage  of  sugar  in 
the  sugar  cane,  there  is  a  larger  percentage  of  wax  ;  more 
sugar  lessens  the  quantity  of  wax.  When  germination 
takes  place,  the  oil  of  the  seeds  is  changed  back  into 
sugar  and  starch  to  nourish  the  plantlet. 

The  proportion  of  fat  in  certain  vegetable  products 
is  given  by  Wolf  and  Knop,  as  follows : 


Maize  fodder  (green)  0.5 

Red  clover  (green)  0.7 

Cabbage  0.4 

Pea  fodder  (dry)  2.0 

Clover  hay  3.2 

Wheat  straw  1.5 

Average  of  all  the  grains  2.6 

Potato  (Irish)  0.3 

Turnip  0.1 

Indian  corn  7.0 

Wheat  1.5 

Rice  0.5 

Oats  6  0 

Peas  2.5 

Barley  2.5 

Winter  rye  2.0 

Pumpkin  0.1 

Beet  ...0.1 


CHAPTER  IX. 

THE  ALKALOIDS,  AND  COLORING  MATTERS  OF  PLANTS. 

193.   The  Alkaloids. 

The  vegetable  alkalies,  or  alkaloids,  formed  in  the 
course  of  vegetation,  always  contain  a  certain  quantity  of 
nitrogen.    They  have  the  general  characteristics  of  alka- 
lies.   They  constitute  salts  by  uniting  with  acids,  and 
10 


218 


CHEMISTRY  OF  PLANTS. 


restore  the  "blue  color  of  reddened  tincture  of  turnsole; 
and  like  ammonia  combine  with  the  hydrates  of  the 
oxacids. 

All  the  vegetable  alkalies  are  soluble  in  alcohol,  and 
generally  insoluble  in  water.  In  elementary  composition 
they  are  very  much  alike,  having  definite  proportions  of 
carbon,  from  50  to  75,  hydrogen  from  6  to  12,  oxygen  8  to 
27,  and  azote  16  to  35  per  cent. 

The  alkalies  doubtless  perform  important  functions, 
existing  as  they  do  in  the  juices  of  plants  with  vegetable 
acids.  Liebig  thinks  that  they  constitute  one  step  in  the 
organization  of  starch,  sugar,  oil  of  turpentine,  and  other 
valuable  bodies  extracted  from  plants.  Thus  the  union  of 
the  constituents  of  water  with  carbonic  acid,  forms  a  sub- 
stance becoming  gradually  poorer  in  oxygen,  the  carbon 
assuming  the  form  of  citric,  malic,  and  other  organic  acids, 
before  being  changed  into  sugar,  lignin,  starch,  etc.  This 
furnishes  a  simple  explanation,  the  necessity  of  alkaline 
bases  in  vegetable  life,  and  constitutes  a  strong  inferential 
evidence  of  their  uses  in  the  organism  of  plants. 

Sertuerner,  in  1804,  first  indicated  the  existence  of  mor- 
phine in  opium,  and  is  entitled  to  the  credit  of  discovering 
the  vegetable  bases. 

We  will  describe  several  of  these  alkaloids  which  are 
of  interest  to  agriculturists. 

194.  Nicotine, 

Nicotine  exists  in  tobacco  in  combination  with  malic 
and  citric  acids.  It  is  derived  from  a  concentrated  solid  oil 
found  in  the  tobacco  plant,  called  nicotianine. 

It  is  a  narcotic  poison,  so  deadly  that  a  single  drop  has 
proven  fatal  to  a  large  dog.  When  pure,  it  is  an  oily, 
colorless  liquid,  has  a  strong  odor  of  tobacco,  and  is  A^ola- 
tile  and  inflammable.  It  has  no  oxygen,  and  contains  17.3 
per  cent,  of  nitrogen.    Some  grades  of  French  tobacco 


COLORING  MATTERS  OF  PLAXTS. 


219 


have  from  7  to  8  per  cent.;  Virginia,  6  to  7  percent.,  and 
Havana,  about  2  per  cent,  of  nicotine. 

Its  centesimal  composition  is  as  follows  :  carbon,  74.07; 
hydrogen,  8.64;  nitrogen,  17.32. 

195.  Caffeine, 

Caffeine  is  found  when  pure  in  white  crystals,  in  tea 
and  coffee  united  with  tannic  acid.  It  occurs  in  tea,  some- 
times as  high  as  6  per  cent.  ;  in  coffee,  only  one-half  per 
cent. 

It  is  the  same  as  theine. 

Its  composition  is  as  follows:  carbon,  49.48  ;  hydrogen, 
5.15;  nitrogen,  28.86;  oxygen,  16.48. 

196.  Theobromine. 

Theobromine  is  found  in  the  cacao  bean,  out  of  which 
chocolate  is  made.  It  has  very  nearly  the  same  chemical 
composition  as  caffeine,  and  resembles  it  in  its  physical 
characters. 

Its  composition  is  :  carbon,  46.66  ;  hydrogen.  4.40  ; 
nitrogen,  31.11,  oxygen,  17.22. 

197.    Coloring  Ma  tiers  o f  Plan  ts. 

The  coloring  matters  of  plants  very  seldom  exist  in  an 
isolated  condition,  but  are  generally  allied  with  some  of 
the  immediate  principles,  which  are  themselves  frequently 
colored.  They  present  great  diversity  of  shades,  but  are 
generally  derived  from  green,  yellow,  and  red.  They  are 
solid;  inodorous,  and  have  but  little  taste.  Some  are  solu- 
ble in  water,  and  others  dissolve  only  in  ether  and  alcohol. 
Several  of  them  unite  with  acids,  and  all  combine  with 
alkalies,  which  have  the  effect  to  modify  their  tints.  Many 
blues,  for  instance,  become  green  or  yellow  under  the 
action  of  the  alkalies,  and  red  under  the  agency  of  acids. 

The  color  of  flowers  depends  to  a  certain  extent  on  the 


2^0 


CHEMISTRY  OF  PLANTS. 


soil  m  which  they  grow.  Yellow  primroses  transplanted 
from  a  poor  to  a  rich  soil,  will  bear  flowers  of  an  intense 
purple.  Charcoal  deepens  the  tints  of  dahlias,  hyacinths, 
and  petunias.  Carbonate  of  soda  reddens  hyacinths,  and 
phosphate  of  soda  changes  the  hues  of  certain  plants  in 
many  ways. 

It  is  a  well-known  fact  that  maize  and  other  plants 
receive  a  much  deeper  tint  of  green,  by  the  application  of 
ammonia  to  the  soil.  This  color  is  always  enhanced  after 
a  rain  succeeding  a  long  dry  spell,  which  is  probably  owing 
to  the  ammonia  brought  down  by  the  showers,  as  well  as 
that  rendered  soluble  in  the  soil. 

198.  Chlorophyl. 

Chlorophyl  (leaf  green)  though  occurring  in  very  mi- 
nute quantities,  is  nevertheless  deemed  to  be  very  impor- 
tant to  vegetation.  It  constitutes  the  green  coloring 
matter  of  the  leaves  and  young  stems  of  all  living  j^lants, 
having  about  the  same  relation  to  them  in  quantity,  that 
the  particles  of  dye  have  to  colored  fabrics.  Berzelius 
supposes  that  the  largest  trees  will  not  contain  more  than 
100  grains. 

It  is  of  the  nature  of  the  vegetable  waxes;  but  often 
decomposes  before  it  melts.  Hydrochloric  and  sulphuric 
acids  will  dissolve  it,  imparting  to  their  liquids  an  intense 
green  color. 

Fremy  says  chlorophyl  may  be  easily  decomposed 
into  two  coloring  matters — one  yellow,  zanthopliyl^  and 
the  other  blue,  cyariophyL  A  mixture  of  hydrochloric 
acid  and  ether  will  efiect  this.  It  is  probable  that  the 
yellow  color  of  autumnal  leaves  is  owing  to  zanthophyl; 
the  cyanophyl  having  been  dissolved  out. 

According  to  Sachs,  those  parts  of  plants  which  are 
not  green,  but  capable  of  becoming  so,  have  a  transparent 
substance,  leitcophyl^  which  is  converted  into  chlorophyl 


DENSITY  AND  COURSE  OF  THE  SAP. 


221 


in  contact  with  oxygen.  This  possibly  accounts  for  the 
fact  that  leaves  growing  in  the  shade  and  just  emerging 
from  the  soil,  as  the  young  cotton  plants,  are  white,  or  of 
a  very  light  green,  owing  to  the  lack  of  decomposition  of 
the  carbonic  acid  by  sunlight  and  consequent  appropria- 
tion of  oxygen  by  the  plant.  Thus  the  bleaching  of  celery 
and  endive,  by  covering  with  the  soil,  excludes  the  oxygen, 
and  leaves  the  leucophyl  in  their  stems. 

An  impure  chlorophyl  obtained  from  grass,  upon  analy- 
sis by  Pfaundler,  had  the  following  composition  :  carbon, 
60.85;  hydrogen,  6.39;  oxygen,  72.78. 


(^.HAPTER  X. 

THE  SAP. — ITS  DENSITY,  COURSE,  AND  CHEMICAL 
COMPOSITION. 

199.  Density  and  Course  of  the  Sap, 

In  botany,  sap  is  defined  as  the  fluid  which  is  absorbed 
by  the  roots  of  plants  from  the  earth,  and  performs  the 
first  action  of  vital  chemistry  toward  their  organism. 

As  soon  as  the  sap  has  penetrated  the  spongioles  of  the 
roots,  very  important  changes  take  place  in  it,  for  chemi- 
cal combinations  are  found  which  could  not  have  existed 
as  such  in  the  water  that  moistened  the  soil.  It  increases 
also  very  rapidl}?-  in  density,  as  Mr.  Knight  found  by 
experiment  that  the  Acer  platanoides,  at  the  level  of  the 
ground  had  a  density  of  1.004,  at  6^  feet  above  it  was 
1.008,  and  at  13  feet  1.012. 

Mr.  Knight  concludes  that  this  increased  density  is  oc- 
casioned by  the  sap  taking  up  nutritive  matter  deposited  in 
the  cellular  tissues.  We  think  a  more  rational  conclusion 
is  that  it  oomes  from  the  appropriation  of  hydrogen  in  the 


222 


CHEMISTRY  OF  PLANTS. 


plant,  and  exhalation  of  water  through  the  pores  of  the 
stem.  By  this  simple  process  of  evaporation  the  sap  be- 
comes concentrated  not  only  in  the  leaves,  but  to  a  cer- 
tain extent  before  it  reaches  the  leaves.  That  which 
remains  is  surcharged  more  heavily  with  important  nutri- 
tive principles,  and  being  now  acted  upon  by  sunlight  and 
air,  and  receiving  heavy  supplies  of  carbonic  acid,  is  elimi- 
nated and  transformed  into  such  salts  as  are  needed  for 
the  growth  of  the  plant. 

The  course  of  the  sap  is  at  first  through  the  tissue  in- 
cluded in  the  bark,  as  long  as  it  is  permeable  ;  the  central 
part  of  the  stem  or  heart  of  trees  especially,  soon  becomes 
chocked  up  or  solidified  by  deposits  of  matter  in  the  tissue, 
and  the  outer  part  of  the  wood  (alburnum)  only  remains 
free  and  open  for  the  circulation  of  the  sap.  The  woody 
tubes  (pleurenchyma)  contained  in  this  part  of  the  tree 
oiFer  the  most  constant  means  for  the  conveyance  of  the 
sap  until  the  plant  reaches  maturity. 

200.  Ascending  and  Descending  Sap. 

The  ascending  sap  consists  of  carbonated  water  and  mi- 
nute portions  of  all  the  salts  entering  into  plant  structure. 

What  is  termed  the  descending  sap  seems  to  be,  from 
recent  experiments,  as  of  doubtful  significance;  as  when 
the  plant  is  in  full  growth  the  juices  are  held  in  equilibrium, 
rising  or  falling  by  hydrostatic  law  as  in  a  cistern,  only 
as  the  vital  force,  and  the  power  of  selection,  changes  the 
soluble  atoms  to  whatever  points  they  are  needed. 

The  carbonic  acid  of  the  air  seems  to  be  imbibed  by  the 
leaves,  absorbed  by  the  juices,  and  decomposed  by  the  sun- 
light for  the  special  building  up  of  the  leaf  organism.  It 
is  probable  that  the  carbon  which  builds  the  growing 
structure  of  the  stem  comes  mainly  from  the  soil.  For  if 
the  sunlight  decomposes  the  carbonic  acid  in  the  leaf  and 
fixes  the  carbon,  how  can  the  insoluble  carbon  be  conveyed 


CHEMICAL  COMPOSITION  OF  THE  SAP. 


223 


hy  the  juices  of  the  plant  to  its  base  ?  If  so  carried,  it  must 
be  as  carbouic  acid  united  with  the  sap,  and  of  course  could 
not  have  been  decomposed  and  fixed  by  sunlight. 

201.    Chemical  Composition  of  the  Sap, 

It  is  very  evident  from  all  the  investigations  that  have 
been  made,  that  the  chemical  qualities  of  the  sap  are  very 
diverse  in  different  plants  and  trees,  as  well  as  different 
seasons  of  the  year,  and  the  stages  of  maturity  of  the  plant 
when  the  analysis  is  made,  as  w^ell  as  the  part  of  the  plant 
in  which  the  sap  exists. 

The  sap  of  the  elm  was  found  to  be  at  the  beginning 
of  April,  mucilaginous,  of  a  yellow  color  and  sweetish 
taste.    Its  analysis  is  as  follows  : 

Water  1027.90 

Acetate  of  potash  9.23 

Organic  matter  1.06 

Carbonate  of  lime  0.80 

So  that  water  constituted  about  988  in  1000  lbs.  of  sap. 

M.  Regimbeau  found  in  the  sap  of  the  vine,  bi-tartrate 
of  potash,  tartrate  of  lime,  mucilage,  and  free  carbonic 
acid.  M.  Biot  found  no  free  carbonic  acid  in  his  experi- 
ments. 

Sugar  has  been  found  in  considerable  quantities  in  the 
sap  of  the  maple  tree,  and  Liebig  and  Will  detected  am- 
moniacal  salts  in  the  sap  of  maple  and  birch  trees. 

Some  trees  and  plants  exude  a  milky  sap,  as  the  paw- 
paw, the  cow  tree,  the  ^^lumeria,  and  the  poppy.  In  the 
latter,  upon  analysis,  was  found,  besides  morphine,  fatty 
matters,  gum,  ulmine,  and  a  woody  substance,  mineral 
salts  with  a  basis  of  lime,  magnesia,  and  potash. 


PAET  YL 

CHEMISTRY  OF  SOILS. 


CHAPTER  1. 

HOST  IMPOKTANT  CONSTITUENTS  OF  SOILS. — EUROPEAN  AND 

AMERICAN    SOILS    CONTRASTED.  PLANT  CONSTITUENTS 

EXHAUSTED  FROM  SOILS. 

202.  American  and  European  Soils  Contrasted. 

Agricultural  chemists  have  laid  it  down  as  a  rule,  that 
the  ingredients  that  are  rarest  in  a  worn  soil,  are  the  first 
exhausted  and  most  needful  to  be  replaced.  This  axiom 
will  do,  if  we  add  to  it  as  well,  that  those  taken  up  most 
abundantly  as  plant-food,  and  existing  most  sj^arsely  in 
soils,  will  be  the  first  exhausted.  Applying  these  two 
rules  we  shall  be  able,  by  getting  an  average  analysis  of 
soils,  and  knowing  the  amount  of  each  element  in  plants, 
to  arrive  at  a  just  estimate  of  the  exhaustion  of  each  from 
cj^ltivated  soils. 

We  present  a  table  of  129  analyses  of  European  and 
American  soils,  from  the  most  reliable  sources,  giving  the 
average  of  the  seven  most  important  constituents  of 
plant-food,  the  only  ones,  in  fact,  ever  needed  to  be  ap- 
plied as  fertilizers.  We  have  separated  the  American 
from  the  European,  because  we  Avished  to  ascertain  the 
relative  amount  of  potash,  as  European  agriculturists 
have  generally  placed  it  in  the  front  rank,  superior,  if 
anything,  to  phosphoric  acid  in  importance,  while  we 


AMERICAN  AXD  EUROPEAN  SOILS  CONTRASTED.  225 


have  found  that  it  was  far  less  valuable  than  the  latter 
substance;  and  that  most  of  our  worn  soils  have  plenty 
of  potash,  if  we  can  get  nitrogen  and  phosphoric  acid. 

It  is  proper  to  state  that  63  of  these  analyses  are  of 
Kentucky  soil,  by  Prof.  Peter,  and  12  by  Prof.  Hilgard, 
of  Mississippi,  taken  from  the  Geological  Reports  of 
those  States.  The  remaining  28  are  by  other  chemists, 
and  divided  between  different  States,  as  follows:  Ohio, 
six;  Maryland,  five;  Mississippi,  four;  Connecticut,  four; 
Canada,  three ;  Georgia,  two  ;  and  one  each  from  Virginia, 
New  York,  Arkansas,  and  South  Carolina. 

Table  showing  the  average  amount  of  the  seven  most 
important  plant  constituents  in  101  American,  and  28 
European  soils. 

American.      European.  Araa4. 

Potash  0.865  0.064  0.718 

Lime  0.626  0.713  0.644 

Magnesia  0 . 801  0.507  0 . 747 

Soda  0.256  0.054  0.216 

Phosphoric  Acid  0 . 200  0 . 055  0 . 173 

Sulphuric  Acid  0 . 139  0 . 079  0 . 128 

Chlorine  0 . 052  0 . 009  0 . 032 


This  table  shows  that  European  soils  have  been  ex- 
hausted of  their  mineral  ingredients  to  a  much  larger 
extent  than  American,  with  the  exception  of  one  single 
constituent,  viz.  lime  :  a  thing  to  be  inferred  from  the 
long  period  during  which  they  have  been  under  cultiva- 
tion ;  and  yet  there  seems  to  have  been  no  reference  made 
to  this  fact  by  any  agricultural  writer. 

Lime  being  still  more  abundant  in  European  soils  after 
the  cultivation  of  a  thousand  years,  shows  the  fact  that 
their  soils  are  much  more  calcareous  than  ours.  It  is 
also  a  fact  well  known,  that  they  apply  lime  profusely  as 
a  fertilizer,  not  as  food  for  plants,  but  as  a  decomposer  of 
10^^ 


226 


CHEMISTRY  OF  SOILS. 


organic  matter  which  abounds  in  all  soils  cultivated  in 
clover  and  small  grain. 

As  to  potash,  we  find  it  existing  in  American  soils  as 
13-|-  to  one  of  European.  Magnesia  nearly  two  to  one; 
soda  nearly  five  to  one ;  phosphoric  acid  nearly  four  to 
one;  sulphuric  acid  nearly  two  to  one,  and  chlorine  nearly 
six  to  one. 

Since  potash  is  so  largely  appropriated  by  plants,  it 
is  easy  to  perceive  why  European  agriculturists  are  so 
loud  in  their  praises  of  its  virtues,  and  yet  phosphoric 
acid  is  still  more  sparse  even  in  their  soils,  although  taken 
up  very  nearly  in  the  same  proportion  by  agricultural 
plants. 

203.    Constituents  of  Plants  Exhausted  from  Soils, 

Carrying  out  the  axiom  above  announced  in  reference 
to  the  value  of  constituents  of  plant-food  in  accordance 
with  their  sparsity  in  soils,  chlorine  would  be  the  most 
important  in  European  soils,  and  then  successively,  soda, 
phosphoric  acid,  potash,  sulphuric  acid,  magnesia,  and 
lime.  In  American  soils  it  would  stand,  chlorine,  sul- 
phuric acid,  phosphoric  acid,  soda,  lime,  magnesia,  and 
potash. 

But  when  we  take  into  the  account  the  percentage  in 
which  these  substances  exist  in  plants  and  are  carried  off 
by  cropping,  we  find  quite  a  change  necessary  to  be  made 
in  our  estimates.  And  with  a  view  to  have  all  the  light 
thrown  upon  this  subject  possible,  we  select  from  the  valu- 
able tables  of  Wolff  and  Knop,  analyses  of  the  leading 
agricultural  crops  in  Europe  and  this  country. 

The  following  table  will  show  the  average  of  the  seven 
most  important  ingredients  in  the  ash  of  agricultural 
plants,  from  all  the  most  trustworthy  analyses  made. 


SEED  AND  PLANT  CONSTITUENTS. 


227 


Potash. 

Soda. 

Magne- 
sia. 

Lime. 

Phos- 
plioric 
Acid. 

Sulphu- 
ric 

Acid. 

Chlor- 
ine. 

XT 

JVlGa.QOw  tlay , . 

.  .  /CO  .  u . 

7  0 

4.9. 

.11 .6. 

9 

5.1 . 

Red.  Clover. , . . 

.  .  .  Otc  .  O  . 

1 

i.  .  U  . 

19,  9 

.  Otc  .  V  . 

Q  Q 

^  0 

.O.I 

Turnips  

. . Oo . o . 

10  4- 

1.^  ^ 

14-  ^ 

4  1 

Wlie3it  Strsiw. . . 

9  fi 

fi  9 

5.4. . 

2.9. 

V/OiL  OllttW  

22.0. 

5.3. 

4.0. 

8.2. 

4.2. 

3.5. 

ST  Kia    V  ilic>s  

.21 .8. 

5.3. 

7.7. 

.37.9. 

7.8. 

5.6. 

.6.1 

Vr  xlcctt  

3.5. 

. .12.2. 

1 

. . 46 . 2 . 

2.4. 

Oaf  e 

V/clLb.. .  

o .  o . 

.     4  .  O  . 

.  o .  o . 

90  7 

1 

Maize  

...27.0. 

.  1.5. 

..14.6. 

.  2.7. 

..44.7. 

.  1.1. 

Peas  

..40.4. 

3.7. 

..  8.0. 

.  4.2. 

..36.3. 

.  3.5. 

.2.3 

Cotton  Seed. . . 

..32.8. 

1.6. 

..13.7. 

.  7.1. 

..32.8. 

.  4.8. 

.0.6 

Cotton  Lint.. . . 

...3t.2. 

.  2.1. 

..  9.3. 

.16.6. 

..  6.8. 

.  3.3. 

.1.7 

The  last  two  items  are  an  average  of  two  recent  analy- 
ses, one  each  by  Professors  White  and  Land. 

204.    Of  Seed  and  Plant  Constitueiits. 

From  this  table  it  appears  that  only  three  constituents 
enter  more  largely  into  the  ash  of  seeds  than  other  parts 
of  the  plants.  These  may  be  well  classed  as  seed  consti- 
tuents, viz.  phosphoric  acid,  potash,  magnesia.  The  table 
would  stand  thus: 

Per  cent,  in  Seed.  Per  cent,  in  Plant, 

Phosphoric  acid  36.1 

Potash  27.4 

Magnesia  11.1 

Lime  -  .4.1 

Soda  2.8 

Sulphuric  acid  2.6 

Chlorine  1.9 


Potash  26.5 

Lime  17.8 

Phosphoric  acid  10.7 

Magnesia  6.3 

Sulphuric  acid  5.4 

Soda  5.1 

Chlorine  3.3 


As  the  seed  is  the  most  valuable  part  of  the  plant,  and 
that  part  which  is  most  commonly  taken  from  the  land 
in  cropping,  it  may  safely  be  estimated  that  elements 
entering  largely  into  the  composition  of  seed  are  of  the 
most  importance,  agriculturally  speaking.  This  would 
make  the  first  column  represent  the  grade  of  the  value  of 
the  different  constituents,  placing  phosphoric  acid  first, 
and  chlorine  last. 


228 


CHEMISTRY  OF  SOILS. 


CHAPTER  II. 

PLANT  CONSTITUENTS  IN  MINERALS,  AND  MINERAL 
CONSTITUENTS  IN  SOILS. 

205.  Plant  Constituents  in  Minerals. 

It  is  a  remarkable  fact  that  phosphoric  acid,  though 
SO  valuable  a  constituent  of  plants,  is  found  very  rarely  in 
minerals  or  rocks  underlying  all  Primary  regions.  True, 
minerals  and  fossils  exist  in  many  localities  containing 
this  substance;  and  in  such  places  as  the  phosphatic  beds 
of  South  Carolina,  it  exists  in  a  much  larger  percentage 
than  any  other  soil  constituent. 

We  have  taken  the  pains  to  investigate  the  subject  by 
an  analysis  of  all  the  minerals  found  commonly  existing 
in  Middle  Georgia,  and  give  the  result  in  a  table  below. 
What  is  true  of  this  region,  will  be  true  of  all  others  with 
the  same  geological  formation. 

Table  showing  the  percentage  of  the  different  organic 
oxides  found  in  the  common  minerals  of  the  Primary  and 
Metamorphic  regions  of  Georgia : 


Minerals.  SiO.  Al^Og.  KO.  MgO.  FeO.   CaO.  NaO.  MnO.  S. 

Quartz  100  

Felspar   67..  19... 14  

Mica   46... 14... 10... 10... 20  

Hornblende   59  20...  7... 14  

Augite   53   8...  17... 22  

Epidote   37... 27  17...  14  

Talc   29... 17  12... 27...  3  

Chlorite   26... 18...  2...  8... 43  

Tourmaline   35... 35   1...18,..  1...  2...  1  

Albite   70... 18  trace..  1 ..  .10.  .trace.. . . 

Garnet   44...  8  12... 33  trace.... 

Iron  Pyrites  47  53 


MINERAL  CONSTITUENTS. 


229 


From  this  exhibit  all  the  inorganic  elements  that  enter 
plants  exist  in  the  rocks  of  Middle  Georgia,  except  phos- 
phoric acid  and  chlorine.  These  are  found  but  sparsely 
in  the  soils,  and  are  doubtless  the  first  exhausted  in  most 
soils,  especially  the  former. 

206.  Mineral  Constituents  per  Acre,  and  their  Period 
of  Exhaustion. 

Estimating  that  an  acre  of  soil  one  foot  deep  contains 
4,000,000  pounds,  we  have  in  American  soils  one-half  foot 
deep,  of  plant  constituents,  as  follows  : 

Potash  17,333  lbs. 

Lime  12,500  " 

Magnesia  16,000  " 

Soda   6,000  " 

Sulphuric  acid   3,400  " 

Phosphoric  acid   3,080  " 

Chlorine   500  " 

Should  a  crop  of  cotton  be  continuously  planted  on  an 
acre  of  ground,  producing  a  half  bale  equal  to  250  lbs.  of 
cotton  fibre,  it  would  take  many  years  to  exhaust  an  average 
American  soil  of  these  mineral  ingredients.  The  follow- 
ing taJDle  shows  the  number  of  years  required  for  each 
substance.  The  estimate  is  made  both  of  the  seed  and  fibre 
taken  from  the  soil. 

Phosphoric  acid   465  years. 

Potash  -  2,595 

Lime  4,671 

Magnesia  6,413 

Soda  6,090 

Sulphuric  acid  4,000 

Chlorine  943 

There  is  no  need  that  the  available  mineral  elements 
should  ever  be  exhausted  from  any  soil.  If  all  the  cotton 
seed,  and  wheat  and  oat  straw  is  returned  to  the  land,  and 


230 


CHEMISTRY  OF  SOILS. 


the  corn  and  cotton  stalks  left  to  rot  upon  it,  there  would 
be  much  less  of  these  principles  extracted  from  the  soil, 
and  it  would  require  but  a  A^ery  small  annual  application 
01  them  to  keep  our  soils  in  good  heart,  and  even  improve 
them  in  their  mineral  wealth,  as  well, as  actual  production. 

207.   Other  Requisites  of  Fertility, 

If  the  fertility  and  value  of  soils  depended  mainly  on 
the  amount  of  mineral  matter  in  them,  we  would  suppose 
that  their  fertility  would  remain  unimpaired  for  centuries 
to  come.  But  it  must  be  remembered  that  there  is  another 
element  more  easily  exhausted  than  any  of  them,  without 
which,  a  soil  would  be  perfectly  barren.  We  refer  to 
nitrogen. 

It  is  also  equally  true  that  these  mineral  elements  must 
be  in  a  soluble  form  or  they  are  not  available.  A  soil 
might  have  enough  phosphoric  acid  in  it  to  supply  the 
crops  for  a  thousand  years,  and  yet  if  not  made  soluble  by 
natural  or  artifical  processes,  the  soil  would  remain  barren, 
though  all  the  other  mineral  constituents,  and  nitrogen  too, 
were  in  abundance,  and  in  soluble  forms. 

And  if  all  these  were  present  with  soluble  phosphoric 
acid,  the  soil  might  yet  be  utterly  worthless  from  the 
absence  of  organic  matter,  to  act  physically  upon  it,  in 
opening  it,  rendering  it  cool  and  moist,  by  absorbing  and 
retaining  water,  as  well  as  ammonia.  This  is  particularly 
true  of  soils  in  warm  climates. 

It  is  thus  perceived  that  the  fertility  of  a  soil  depends 
upon  a  number  of  contingencies,  all  of  which  must  trans- 
pire in  order  for  a  soil  to  be  productive. 


COARSE  AND  FINE  SOILS. 


231 


CHAPTEE  III. 

SOLUBILITY  OF  SOILS.  EXHAUSTION  OF  SOILS. 

208.   Coarse  and  Fine  Soils, — Soluble  and  Insoluble, 

If  a  sample  be  taken  from  common  arable  soil,  and 
thoroughly  dried,  and  sifted  in  a  fine  sieve,  it  will  be  found 
that  much  the  larger  portion  will  remain  as  fragments  of 
roclvS,  coarse  pebbles,  and  small  grains  of  sand.  These 
pebbles  when  properly  disintegrated  will  be  quite  as  valu- 
able as  the  silt  or  finer  particles,  and  an  analysis  would 
doubtless  show  all  the  constituents  of  plant  food  in  good 
proportions.  They  may  be  considered  as  the  reserved 
forces,  held  in  store  for  future  use.  They  have  no  agri- 
cultural value  however,  only  prospectively  and  in  the  far 
future. 

The  finer  particles  of  soil  which  escape  through  the 
sieve,  are  of  much  higher  value,  being  the  part  from  w^liich 
crops  have  to  draw  upon  for  nutriment.  And  even  this, 
how^ever  fine,  is  divisible  into  three  parts;  the  first  soluble 
in  water,  the  second  in  acids,  and  the  third  insoluble. 

The  portion  soluble  in  w^ater  is  that  upon  which  the 
present  crops  feed,  and  find  sustenance.  This  is  generally  in 
the  finest  atomic  condition.  In  fact  some  chemists  incline 
to  the  opinion  that  mineral  substances  may  be  reduced  to 
such  impalpable  atoms,  as  that  they  may  be  appropriated 
as  plant  food  without  any  change  in  their  form.  We  can- 
not think  so,  however.  We  do  not  believe,  for  instance, 
that  the  tribasic  phosphate  of  lime  could  be  rendered  fit 
food  for  plants  by  mere  mechanical  fineness.  That  con- 
dition renders  it  in  a  much  better  state  to  become  soluble 
by  ammonia,  carbonated  water,  or  solution  of  chloride  of 


232 


CHEMISTRY  OF  SOILS. 


sodium  in  the  soil.  But  the  form  is  changed  by  these 
solvents  and  thus  it  becomes  fit  food  for  plants. 

209.   Of  Soluble  Matters  in  Soils, 

Prof.  Johnson  gives  an  interesting  estimate  made  of 
various  soils,  as  to  the  amount  of  matters  in  those  soluble 
in  water.  (How  Crops  Feed,  p.  311.) 

Seventeen  different  analyses  show  an  average  of  the 
following  substances  in  100,000  parts  of  various  soils: 

Lime  38.3         Sulphuric  acid  35.9 

aesia  7.9  Silica  14.1 


Potash  8.8  Oxide  of  iron  7.5 

Soda  40.2  Organic  matter  80.2 

Phos.  acid  0.9  Total  soluble  303.9 

Chlorine  51.3 

Of  lime,  every  soil  had  1  part  or  more. 
Of  magnesia  one  soil  had  only  a  trace,  and  one  other 
under  ^, 

Of  potash  only  one  had  less  than  one  part,  having  -J. 

Of  soda  one  soil  was  a  salt  marsh  having  476  parts. 
The  others  ranged  from  1  to  24. 

Of  phosphoric  acid  four  soils  had  not  a  particle  soluble 
in  water;  five  others  only  a  trace,  one  other  of  one  part, 
another  -J,  the  remaining  six  ranging  from  1  to  5  parts. 
How  clearly  this  shows  the  value  above  all  others  of  phos- 
phoric acid  as  a  fertilizer,  and  the  need  of  its  being  ren- 
dered soluble  by  the  intervention  of  science. 

The  same  remark  is  true  of  chlorine,  as  of  soda,  the 
saft  marsh  running  up  to  407,  all  the  others,  (except  five 
which  had  only  a  trace)  ranging  from  1  to  7|^. 

Of  sulphuric  acid  one  soil  had  302,  another  salt  meadow 
144,  two  others  a  trace,  the  remainder  ranging  from  1  to  18. 

Of  silica  three  soils  had  only  a  trace ;  the  others 
ranging  from  1  to  58. 

Of  oxide  of  iron,  four  soils  had  none,  the  rest  of  them 
ransjino^  from  1  to  77. 


EXHAUSTION  OF  SOILS. 


233 


Of  organic  matters,  the  lowest  was  10,  the  highest  44.9. 

Take  the  17  different  soils,  the  one  lowest  in  soluble 
matters  was  39|  parts,  the  highest  1393,  equal  to  1.393  per 
cent. 

The  quantity  of  soluble  matters  was  as  a  general  rule 
greatest  in  damp  soils  abounding  in  organic  matters.  I^ext 
in  fertile  soils,  either  natural  or  made  so  by  manures,  and 
the  least  in  poor  sandy  soils. 

210.  Exhaustion  of  SoUs. 

We  now  propose  to  notice  a  little  more  in  detail  the 
exhaustion  of  soils  by  cropping.  We  have  seen  that  nitro- 
gen is  supplied  to  plants  by  their  roots,  and  that  it  is  the 
only  organic  element  needed  to  be  supplied  to  soils,  or  that 
can  be  exhausted  from  them.  Then  the  nitrogen  of  plants 
is  furnished  at  the  expense  of  the  soil.  With  this  excep- 
tion, certain  mineral  elements,  constitute  the  entire  amount 
of  matters  taken  up  by  croj^s,  which  produce  the  exhaustion 
of  soils.  Then  the  mineral  theory  of  Liebig  must  be  re- 
ceived with  this  much  modification,  that  the  nitrogen  fur- 
nished by  organic  matters  in  the  soil,  or  applied  to  them 
in  fertilizers  is  quite  as  essential  as  the  minerals,  inasmuch 
as  the  atmosphere  cannot  supply  it  directly. 

We  have  seen  that  the  mineral  substances  of  most  im- 
portance to  plants,  are  phosphoric  acid,  potash,  magnesia, 
lime,  soda,  sulphuric  acid  and  chlorine.  These  exist  in  the 
sparsest  quantities,  and  all  of  them  may,  under  certain  cir- 
cumstances, become  exhausted  from  soils,  so  as  to  require 
replenishing.  This,  we  believe,  is  never  true  of  silica, 
alumina,  manganese  and  iron. 

Mineral  substances  can  only  be  exhausted  from  a  soil, 
by  cropping,  if  we  except  soluble  matters,  Avhich  are  some- 
times leached  out  of  certain  soils,  and  carried  beyond  the 
reach  of  plants.  All  cultivated  soils  lose  more  or  less  by 
crops  that  are  carried  off  from  them.    When  the  entire 


234 


ClIEMISTEY  OF  SOILS. 


plant  is  returned  to  the  soil,  it  rather  enriches  than  im- 
poverishes it,  by  increasing  the  amount  of  organic  matter 
taken  from  the  atmosphere,  and  increasing  the  amount  of 
available  mineral  food. 

We  now  present  a  statement  of  the  amount  of  the  most 
important  mineral  substances,  as  well  as  of  nitrogen  carried 
off  by  different  field  crops. 

A  crop  of  750  lbs.  of  seed  cotton  will  carry  off  from  one 
acre  of  land  23.25  lbs.  of  nitrogen,  and  35.3  lbs.  of  ash;  of 
which  there  will  be  of  the  most  important  mineral  elements, 

Potash  8.30       Magnesia  5.05       Sulph.  acid... 0.50 

Soda  3.20       Chlorine  0.30       Plios.  acid  .  ..7.20 

Lime  0.83 

A  crop  of  8^  bushels  of  wheat  and  an  equal  quantity 
by  weight  of  straw,  will  carry  off  from  an  acre  of  land,  in 
pounds, 

Nitrogen  11.50       Magnesia  0.74       Lime  0.46 

Soda  0.31       Sulphuric  acid  0.26       Chlorine  trace 

Phos.  acid. . .  .2.57       Potash  2.12       Total  ash. . .  .35.15 

A  crop  of  Indian  corn  in  the  ear  equal  to  nine  bushels 
of  the  grain,  will  carry  off  from  an  acre  of  land,  in  pounds, 

Nitrogen  9.00       Magnesia  0.76       Lime  0.18 

Soda  0.09       Sulphuric  acid  0.09       Chlorine  trace 

Phos.  acid  2.27      Potash  2.13       Total  ash  7.94 

A  crop  of  oats,  grain  and  straw,  allowing  that  the 
weight  of  the  straw  is  double  that  of  the  grain,  the  crop 
being  12  bushels  per  acre,  will  carry  off  of 

Nitrogen  12.0        Lime  1.62       Phos.  acid.  . .  .2.27 

Magnesia  . .  .12.0        Soda  1.52       Sulph.  acid. .  .0.59 

Chlorine  trace       Potash  4.72       Total  ash  . .  .32.76 

A  crop  of  peas,  consisting  of  the  seed,  equal  to  nine 
bushels  per  acre,  will  carry  off  the  following  amount  of 
nitrogen  and  mineral  substances : 

Nitrogen  16.50       Magnesia  0.40       Lime  0.21 

Soda  0.18       Sulphuric  acid  0.17       Chlorine  0.11 

Phosph.  acid  .1.81       Potash  2.02       Total  ash  . .  .14,05 


WATER  CHEMICALLY  CONSIDERED. 


23e5 


Here,  then,  we  have  the  principal  field  crops  in  the 
South  rated  at  about  their  average  annual  production. 
Nitrogen,  phosphoric  acid,  and  potash,  being  confessedly 
the  most  valuable  substances,  will  be  exhausted  from  the 
soil  by  cotton  in  four  successive  crops,  per  acre,  as  follows: 
Nitrogen,  92.80  lbs.;  phosphoric  acid,  28.80;  potash,  33.20. 
A  rotation  of  crops,  1st  cotton,  2d  wheat,  3d  coi'u  and 
peas,  4th  oats,  will  abstract  of  nitrogen,  72.25;  of  phos- 
phoric acid,  15.12  ;  of  potash,  19.29. 

Thus  it  will  be  seen  that  running  land  in  cotton  exclu- 
sively for  four  years,  will  leave  the  land  poorer  in  nitrogen 
by  20.55  lbs.;  in  phosphoric  acid  by  12.78,  and  in  potash 
by  13.91,  than  to  have  the  rotation  of  five  crops  above  men- 
tioned, in  four  years. 

These  amounts  taken  mostly  from  the  surface  soil,  not 
more  than  six  inches  deep,  seem  very  small  in  comparison 
with  the  whole  amount  of  these  substances  found  in  most 
soils,  but  when  subtracted  from  the  available  nitrogen, 
phosphoric  acid,  and  potash  of  even  the  richest  soils,  it 
produces,  as  our  experience  too  well  teaches  us,  a  most 
rapid  deterioration. 


CHAPTER  ly. 

WATER  AS  A  CHEMICAL  AGENT  IX  SOILS.  CHEMICAL 

ABSORPTION  OF  SOILS. 

211.    Water  Chemically  Considered, 

We  have  now^  treated  of  all  the  constituents  of  soils 
useful  to  vegetation,  except  water,  and  that  is  by  no 
means  the  least  important.  In  fact  it  is  of  such  impor- 
tance that  no  germ  could  sprout,  and  no  vegetation  sub- 
sist without  it. 


236 


ClIEMISTKY  OF  SOILS. 


In  chemical  language,  water  is  the  23rotoxide  of  hydro- 
gen. The  old  formula  was,  H0=9,  one  equivalent  of 
hydrogen,  and  one  of  oxygen.  Under  the  new  regime  it  is 
H.^0=18,  two  atomic  weights  of  hydrogen  and  one  of  oxy- 
gen.   Its  centesimal  composition  is 

Oxygen  88.88 

Hydrogen  11.11 

100.00 

By  measure,  water  has  one  volume  of  oxygen  to  two 
of  hydrogen. 

Water  may  be  formed  by  the  burning  of  hydrogen  gas. 
It  is  first  mingled  with  vapor  of  water  in  a  suitable  appa- 
ratus, and  made  to  stream  slowly  through  a  wide  tube,  filled 
with  fragments  of  dried  chloride  of  calcium,  which  cause 
its  dessication.  After  the  displacement  of  the  air,  the  gas 
is  ignited  at  the  upper  end  of  the  tube,  and  a  bell-glass 
suspended  over  the  flame,  on  which  water  will  be  collected 
as  dew,  and  soon  flow  down  in  drops  into  a  vessel  placed 
beneath. 

Water  exceeds  any  other  liquid  in  nature  as  a  solvent. 
It  combines  with  saline  substances,  as  water  of  crystalliza- 
tiorij  forming  liydrates  by  chemical  union  with  other  sub- 
ijtances.  This  is  generally  attended  with  heat,  as  when 
lime  is  slaked,  by  which  a  hydrate  of  lime  is  formed, 

212.    'Water ^  Gaseous^  Liquid^  Solid. 

Water  occurs  in  nature  under  three  forms  :  gaseous, 
liquid,  and  solid.  The  first  is  the  watery  vapor  of  the  at- 
mosphere ;  the  second,  limpid,  fluid  water;  the  third,  frozen 
water,  or  ice. 

When  pure,  water  is  colorless,  transparent,  and  without 
taste  or  odor.  And  yet  there  is  something  so  refreshing 
in  a  cool  draught  of  water,  that  it  is  very  grateful  to  the 
palate. 


CHEMICAL  ABSOPvPTIOX  OF  SOILS. 


237 


It  freezes  at  32^  F.  when  slightly  agitated,  but  when 
perfectly  at  rest,  at  a  lower  temperature.  Its  densest  point 
is  40°,  boils  at  212°,  and  evaporates  at  all  inferior  tem- 
peratures. 

In  the  construction  of  ice,  which  is  lighter  than  Avater 
(having  a  specific  gravity  of  0.918),  we  can  see  the  wisdom 
of  an  Infinite  mind  so  clearly  portrayed,  that  even  the 
materialist  must  acknowledge  in  it  an  intelligent  design. 
It  is  a  general  law  of  nature  that  all  gaseous  and  liquid 
substances  in  becoming  solid,  become  more  dense.  lee 
is  an  exception  to  this  rule.  Should  it  have  been  differ- 
ently constructed,  it  would,  as  fast  as  congealed  at  the 
surface  of  tlie  northern  lakes  and  rivers,  have  sunk  to 
tlie  bottom  never  to  rise  again,  and  never  to  be  thawed, 
Tlius  would  not  only  all  the  northern  regions  have  become 
frozen,  but  it  would  have  extended  the  line  of  perpetual 
winter  to  the  temperate  and  even  torrid  zones. 

The  great  value  of  water  to  soils,  not  only  by  furnish- 
ing hydrogen  and  free  water  to  plants,  but  by  rendering 
soluble  all  nutrient  elements  taken  up  as  plant-food,  as  well 
as  its  effects  as  a  physical  agent  in  the  soil,  have  already 
been  fully  discussed  in  this  work. 

213.    Chemical  Absorption  of  Soils. 

Soils  have  a  power  which  has  been  termed  chemical 
absorption,  by  which  they  imbibe  and  retain  from  the 
atmosphere  and  fertilizers  applied  to  them,  the  most  valua- 
ble salts,  which  will  be  needed  for  plant-food.  This  power 
is  possessed  by  aluminous  soils  to  a  liigher  degree  than 
silicious  soils.  An  excess  of  soluble  matters  may  thus  be 
appropriated  and  reserved  for  a  time  of  want. 

From  various  experiments  made  by  Liebig,  Yoelcker, 
Eichhorn  and  others,  the  following  facts  have  been  elicited 
in  reference  to  this  absorptive  power  of  soils  on  different 
salts. 


238 


CHEMISTRY  OF  SOILS. 


Oxide  of  iron  and  alumina  absorb  ammonia  and  hold 
it  in  a  slightly  soluble  state. 

Free  ammonia  and  its  carbonate,  are  retained  by  the 
organic  acids  in  a  non-volatile  form. 

The  sulphate,  hydrochlorate  and  nitrate  of  ammonia, 
are  decomposed  by  the  soil,  the  ammonia  retained,  and 
the  acids  united  to  lime. 

Phosphoric  and  silicic  acid  are  also  retained,  and  sul- 
phuric and  hydrochloric  acids  are  also  said  to  be  liable  to 
absorption.  In  no  case,  however,  has  nitric  acid  been  ab- 
sorbed and  fixed. 

Salts  of  lime,  especially  when  added  alone  to  the  soil, 
ro  to  a  soil  rich  in  lime,  are  said  not  to  be  absorbed.  The 
carbonate  of  lime,  however,  and  lime  itself  are  held  by  the 
organic  acids  of  the  soil  as  humic,  crenic,  etc. 

In  a  dilute  solution  of  chloride  of  ammonium  for  ten 
days,  the  mineral  took  up  3.83  per  cent,  of  ammonia;  and 
in  twenty-one  days  it  yielded  6.94  per  cent,  with  a  loss  of 
water. 

These  and  similar  experiments  have  established  with- 
out doubt,  that  the  hydrous  double  silicates  in  all  soils 
determine  the  absorption  and  retention  of  potash,  ammonia, 
etc.,  from  solutions  of  their  salts. 

It  is  known  also,  that  insoluble  phosphates  and  sili- 
cates are  formed  with  oxide  of  iron,  alumina,  lime,  and 
magnesia,  under  certain  conditions.  Sulphuric  acid  also 
forms  insoluble  combinations  with  iron  and  alumina. 

We  are  justified  then  in  the  conclusion  that  all  clay 
soils  are  capable  of  imbibing  and  fixing  all  the  ammonia, 
potash,  and  phosphoric  acid,  that  is  likely  to  be  brought 
into  the  soil  by  any  means  w^hatever.  This  cannot  be 
true  of  sandy  soils  ;  nor  are  clay  soils  so  retentive  of  am- 
monia in  southern  as  in  northern  climates. 

It  is  also  probable  that  these  bodies  are  never  com- 
pletely removed  from  the  most  dilute  solution  ;  and  thjit 


SOURCES  OF  NITKOGEX. 


239 


when  a  soil  has  become  saturated  with  them,  it  lets  them 
off  slowly  to  i^iire  water,  or  acid  solution,  by  which  means 
plants  receive  their  food. 


CHAPTER  V. 

NITROGEN  IN  SOILS. 

214,  Sources  of  Nitrogen, 

Nitrogen  exists  in  three  forms  in  soils,  viz.  nitrogen, 
ammonia,  and  nitric  acid.  Nitrogen  gas  is  developed 
sometimes  from  the  ground  in  certain  localities,  but  rarely, 
owing,  as  is  supposed,  to  the  decomposition  of  air  in 
cavernous  rocks.  The  nitrogen  and  oxygen  uniting  to 
form  nitric  acid,  a  large  excess  of  nitrogen  is  thus  left  and 
evolved  from  the  soil.  (Shepard.) 

It  is  also  evolved  from  many  well-known  springs,  as 
Cheltenham  and  Ilarrowgate. 

Nitrogen  exists  in  all  kinds  of  soils,  and  in  mineral^ 
which  were  never  in  contact  with  organic  substances. 
But  its  principal  source  in  soils,  we  doubt  not,  is  from  the 
decay  of  vegetable  and  animal  organisms. 

When  we  remember  how  many  human  beings  are 
buried  beneath  the  ground,  how  many  worms,  insects,  and 
reptiles,  also  die  and  decay  in  the  soil,  as  well  as  the  nu- 
merous birds  and  beasts  that  rot  upon  its  surface,  from 
whose  carcases  more  or  less  of  the  nitrogen,  as  ammonia 
or  nitric  acid,  is  imbibed;  we  see  what  a  continued  supply 
is  being  furnished  from  these  sources. 

The  urine  and  excrement  also  of  every  living  being,  is 
constantly  imparting  nitrogen  in  one  of  these  three  forms 
to  the  soil. 

We  have  a  notable  instance  of  these  sources  of  nitro- 


240  CHEMISTRY  OF  SOILS. 

gen  in  the  Chincha,  Guanape,  and  other  islands  of  Peru, 
where  a  species  of  sea  fowl  have  been  wont  for  ages  to 
congregate.  Carrying  thither  the  fishes  of  the  sea  upon 
which  they  prey,  and  then  in  their  turn  sicken  and  die; 
fish  and  fowl,  flesh  and  bones  and  excrement,  all  com- 
mingling, form  the  most  powerful  fertilizer  known,  with 
just  about  as  much  silica  as  the  gizzards  of  these  birds 
would  require  to  aid  in  digesting  their  food.  These  rich 
deposits  contain  from  4  to  18  per  cent,  of  nitrogen. 

In  the  same  country,  in  the  district  of  Tarapaca,  im- 
mense beds  of  the  nitrate  of  soda  have  been  found,  which 
is  transported  to  this  country  and  Europe  for  fertilizing 
purposes. 

215.    Organic  Nitrogen  in  Soils. 

Boussingault  has  shown  conclusively  that  nitrogen 
exists  largely  in  many  soils  in  an  insoluble  form.  This 
organic  nitrogen,  however,  may  be  made  assimilable  in 
two  ways  :  first,  by  oxidation,  which  converts  the  nitrogen 
into  nitric  acid,  through  heat,  moisture,  and  vegetable 
putrefaction ;  second,  the  application  of  lime  and  alkalies, 
which  reduces  the  nitric  acid  by  a  rapid  putrefactive  de- 
composition to  ammonia.  A  soil  saturated  with  water, 
thus  excluding  the  air,  would  favor  this  reduction,  but 
as  the  soil  becomes  dry,  nitric  acid  would  form  again, 
rapidly. 

The  albuminoids  probably  furnish  most  of  the  organic 
nitrogen  of  soils. 

Natural  humus  is  never  destitute  of  nitrogen.  The 
acids  of  humus,  crenic,  apocrenic,  humic,  and  ulmic,  them- 
selves free  from  nitrogen,  are  naturally  combined  with 
ammonia ;  but  this  is  so  fixed  as  to  be  difficult  of  separa- 
tion. Carbon  and  hydrogen  evolve  more  rapidly  from 
decaying  organic  matter  than  nitrogen;  hence  the  nitrogen 
in  humus  is  relatively  larger  than  the  carbon. 

Kroker  analyzed  22  diiferent  soils,  and  found  nitrogen 


COMPOUNDS  OF  NITROGEN  IN  SOILS.  241 

ill  all  of  them  in  considerable  quantities.  An  unfruitful 
sand  contained  a  hundred  times  more  nitrogen  than  is 
necessary  for  a  good  crop.  In  all  arable  soils  there  were 
present  500  to  1,000  times  more  nitrogen  than  was  neces- 
sary. 

Schmid  found  a  black  soil  of  Prussia  to  contain  0.99 
per  cent,  of  nitrogen. 

Nitrogen  exists  mostly  in  the  surface  soil,  which  is 
denominated  the  tilth,  gradually  diminishing  the  deeper 
you  go  down  ;  so  that  below  the  depth  of  10  inches,  it 
exists  in  infinitesimal  quantities,  if  at  all.  This  is  prima 
facie  evidence  that  the  atmosphere  is  its  principal,  if  not 
only  source. 

When  it  is  known  that  soils  rich  in  organic  matter 
have  from  5,000  to  35,000  lbs.  of  inert  nitrogen,  how  im- 
portant to  learn  the  cheapest  process  to  convert  this  nitro- 
gen into  soluble  forms,  rather  than  spend  so  many  millions 
to  bring  it  from  Peru. 

216.    Compounds  of  Nitrogen  in  Soils, 

Salts  of  ammonia,  nitrates,  and  nitrites,  as  far  as  known, 
are  the  only  compounds  of  nitrogen  existing  in  soils,  and 
these  in  minute  quantities.  Where  humus  abounds,  the 
amount  of  nitrogen  is  greatly  increased.  In  32  specimens 
of  peat  free  from  earthy  matters,  Prof.  Johnson  found  the 
average  2.6  per  cent.  ;  in  some  cases  as  high  as  4.31. 
Most  of  this  belonged  to  the  humus  as  nitrogen;  a  mi- 
nute portion  only  was  in  the  form  of  ammonia,  or  the 
nitrates. 

Nitrogen  accumulates  in  rich  soils,  but  is  mostly  insol- 
uble. Boussingault  found  only  four  per  cent,  in  such 
soils  existini^  as  nitrates  or  ammonia,  the  remainder  beino; 
unavailable  to  plants.  He  also  analyzed  a  number  of  soils 
w^ith  reference  to  the  amount  of  ammonia,  nitrate  of  potash, 
11 


242 


CHEMISTRY  OF  SOILS. 


and  nitrogen.    We  select  several  analyse?  of  different 

classes  of  soils,  as  follows  : 

Soils,  Ammonia.     Nitrate  of  Potash.  Nitrogen 

at  the  depth  of  one  foot.    Lbs.  per  acre.      Lbs.  per  acre.        in  combination. 

Light  garden  soil  100  875  12,970 

Wheat  field,  clay   45   75   6,985 

Rich  past ure  300  230  25 .650 

Heavy  forest  clay  183   5   5,955 

Fine  sand,  prairie  190   5   3,440 

Loam,  near  Amazon. ..... .210  none   9,100 

Rich  leaf  mould  2,875  none  34,250 

From  this  table,  ammonia  is  generated  largely,  more 
in  the  rich  leaf  mould  than  elsewhere,  while  of  nitric  acid 
there  is  none.  This  was  probably  owing  to  constant 
nloisture — a  state  adverse  to  nitrification. 

Boussingault  found  in  100  parts  of  rich  garden  mould, 
that  had  been  cultivated  for  many  years. 

Nitrogen  0.261 

Ammonia  ,  0.0022 

Nitric  acid  0.00034 

This  distinguished  experimenter  found  that  only  the 
ammonia  and  nitric  acid  were  of  present  use  to  vegetation. 
The  remainder  being  for  the  time  inert. 

So  variable  is  the  assimilable  nitrogen  of  a  soil,  that 
no  estimate  can  be  made  of  it  as  a  constant  quantity. 
Bretschneider  experimented  during  the  growing  months 
to  ascertain  this  fact.  He  found  that  ammonia  decreased 
rapidly  from  April  to  September  in  porous  soils  and  slowly 
in  compact  soils.  That  nitric  acid  obtained  its  maximum 
in  June,  and  fell  to  nothing  in  September.  The  oat  plot 
had  59  of  ammonia  in  April,  and  only  seven  in  September, 
the  reduction  being,  gradual;  the  uncultivated  plot  falling 
from  59  to  23.  The  nitric  acid  in  the  oat  plot  fell  from 
66  to  naught,  and  the  same  in  the  vacant  plot ;  but  in 
June  the  latter  had  108,  the  former  only  57. 

The  total  nitrogen  of  the  soil  in  the  uncultivated  plot 


AMMONIA  IN  SOILS. 


243 


increased  from  April  to  September  from  4,652  to  6,525,  show- 
ing that  the  latter  gathered  nitrogen  more  rapidly  from 
the  atmosphere  in  some  way.  Also  that  ploughed  lands 
will  increase  more  rapidly  in  nitrogen  than  those  lying 
fallow.    This,  however,  requires  further  demonstration. 

Ammonia  and  nitric  acid  are  the  exclusive  sources  of 
nitrogeneous  food  for  plants — the  organic  nitrogen  hav- 
ing to  be  converted  into  one  of  these  forms  before  it  is 
available.  Boussingault  experimented  with  his  own  gar- 
den soil,  which  contained  26  per  cent,  of  nitrogen,  equiva- 
lent to  7  tons  of  ammonia  per  acre.  This  soil  in  small 
quantities,  when  shielded  from  rain  and  dew  did  not  de- 
velop plants  but  little  farther  than  a  barren  sand.  In  eight 
trials  the  crops  weighed  on  an  average  four  times  as  much 
as  the  seed,  while  in  sand  and  burned  soils  containing  no 
nitrogen,  the  crops  weighed  three  times  more  than  the 
seed.  The  available  nitrogen  in  this  garden  soil  was  as  19 
to  2,610  unavailable. 

It  is  believed  that  under  peculiar  circumstances,  the 
nitrogen  of  ammonia  and  of  tlie  nitrates  may  pass  into 
organic  coml)ination  in  the  soil,  forming  an  amide — like  sub- 
stance w^ith  the  humus.  Knop  demonstrated  that  ammonia 
kept  in  close  vessels  with  humus  would  entirely  disappear 
in  the  course  of  several  months.  Other  experiments  of 
Hunt,  Dusart,  and  Thenard  prove  that  ammonia  as  a  car- 
bonate in  prolonged  contact  with  cellulose  and  humic  acid 
forms  combinations  which  may  be  reproduced  by  the  action 
of  the  alkalies  and  lime. 

217.  Armnoiiia  in  Soils, 

Ammonia  exists,  to  a  limited  extent,  in  all  soils  that 
have  any  productive  capacity,  though  Knop  asserts  that 
clay  is  the  only  ingredient  of  soils  which  absorbs  ammonia, 
and  that  all  carbonate  of  ammonia  found  in  soils,  adheres 
to  clay. 


244 


CHEMISTRY  OF  SOILS. 


The  quantity  of  ammonia  in  a  soil  is  small  and  variable, 
always  increased  by  dew  and  rain,  as  well  as  by  the  appli- 
cation of  manures  ;  and  decreased  by  evaporation. 

It  is  most  probably  true,  that  ammonia  as  such,  is  re- 
tained by  the  alumina  of  a  soil,  its  humus  and  the  hygro- 
scopic water  existing  in  it.  And  besides  its  combining 
with  acids  foi*ming  sulphates,  phosphates,  carbonates,  etc., 
it  undergoes  the  process  of  nitrification. 

Soils  boiled  with  solutions  of  potash,  yield  ammonia  for 
a  long  period.  Lime  incorporated  with  soils  at  a  common 
temperature  increase  its  ammonia.  In  one  experiment  a 
quantity  of  soil  with  lime  and  water,  confined  for  eight 
months,  increased  from  11  to  303  milligrames  of  ammo- 
nia. (Boussingault.) 

Ammonia  is  a  constant  constituent  of  minerals  contain- 
ing iron.  Hematite  and  common  iron  ore  are  said  to  con- 
tain one  per  cent,  of  ammonia,  and  also  soils  containing 
oxide  of  iron  and  clay  have  more  or  less  of  this  salt. 

Bonis  says  that  the  peculiar  odor  emitted  by  moisten- 
ing minerals  containing  alumina  originates  in  part  irom 
ammonia.  This  is  always  discernible  in  the  first  fall  of 
summer  showers  after  a  dry  spell  on  the  impalpable  dust 
of  a  street  or  well-trodden  road. 

Humfield  found  the  carbonate  and  nitrate  of  ammonia 
in  the  springs  at  Eldena  in  Germany,  and  pharmaceutical 
chemists  have  often  detected  it  in  well  water. 

218.  Nitric  Acid  in  Soils, 

Nitric  acid  exists  in  soils  as  a  very  inconstant  quantity, 
undergoing  rapid  changes,  being  formed  from  ammonia 
and  then  uniting  with  bases  forming  nitrates. 

The  nitrates  are  very  soluble,  and  leach  out  of  soils  by 
heavy  rains.  In  100  analyses  of  lake,  river,  spring,  and 
well  water,  Boussingault  found  nitric  acid  in  every  case — 
the  quantity  being  the  largest  in  cities  and  fertile  regions. 


NITROUS  ACID  IN  SOILS. 


245 


Thus  the  Seine  had  six  times  as  much  nitrate  of  potash  as 
the  Rhine,  and  the  Nile  four  times  as  much.  He  esti- 
mated that  the  Rhine  and  its  tributaries  carried  to  the 
sea  220  tons  of  saltpetre  daily,  the  Seine  270,  and  the  Nile 
1,100. 

Nitric  acid  exists  also  in  minerals  in  combination  with 
lime,  magnesia,  potash,  and  soda.  This  latter  forming 
large  beds  in  some  localites. 

We  will  treat  of  this  subject  more  fully  when  we  come 
to  natural  fertilizers  under  the  head  of  Nitrification. 

219,  Nitrous  A  cid  in  jSoils. 

Chabrier  ascertained  by  analysis  that  all  tilled  soils 
contained  nitrous  acid.  The  soils  were  powdered  very  fine, 
passed  through  a  sieve,  and  then  bleached  in  order  to  make 
the  determination. 

It  is  well  known  that  nitric  acid  is  acumulated  in  dry 
weather  in  the  superficial  strata  of  the  earth ;  the  reverse 
being  true  of  nitrous  acid.  Hence  it  would  seem  that  the 
soluble  nitrites  ascend  by  capillarity  in  the  soil  during  dry 
weather,  where  they  are  transformed  into  nitrates,  and  then 
washed  out  by  the  rain. 

One  part  of  nitrous  acid  to  25,000  parts  of  water  is  gen- 
erally found  in  soil  water  ;  never  more  than  one  part  in 
5,000.  Fields  which  have  not  been  ploughed  for  some  time 
contain  much  nitric,  and  but  little  nitrous  acid  j  while  the 
reverse  is  true  of  forest  lands.  Clay  soils  which  have  been 
submerged  contain  no  nitrous  and  but  little  nitric  acid. 
Nitric  acid,  though  occurring  in  such  a  small  percentage, 
is  of  importance,  especially  in  the  early  stages  of  vegeta- 
tion. 


240 


CHEMISTRY  OF  SOILS. 


CHAPTER  VI. 

ANALYSIS  OF  SOILS  A  DUBIOUS  TEST  OF  FERTILITY. 
NEW  METHOD  OF  SOIL  ANALYSIS. 

220.  Analysis  of  Soils  a  Dubious  Test  of  Fertility, 

ITeeetofore  chemistry  has  never  been  able  to  define 
exactly  the  laws  which  govern  fertility.  Liebig,  who  de- 
voted a  long  life  to  agricultural  chemistry,  in  one  of  his  last 
works  says,  "  Chemical  analysis  gives  but  rarely  a  correct 
standard  by  which  to  measure  the  fertility  of  different  soils, 
because  the  nutritive  substances  therein  contained,  to  be 
really  available  and  effective,  must  have  a  certain  form  and 
condition,  which  analysis  reveals  but  imperfectly." 

All  the  chemical  constituents  of  which  plants  are  formed 
may  be  present  in  a  soil,  and  yet  it  be  unproductive.  They 
must  be  in  certain  soluble  and  available  forms  which  chem- 
istry cannot  fully  define.  And  even  soils  having  less  of 
these  available  matters  may  be  more  productive  than  others 
having  more  of  them,  owing  to  certain  physical  defects 
existing  in  the  one  from  which  the  others  are  free. 

As  illustrative  of  this  general  principle,  you  may  take 
a  stiff  clay  soil  and  a  sandy  loam,  and  have  them  analyzed. 
The  leading  principles  of  plant-food  exist  more  abundantly 
in  the  clay  than  in  the  sand.  You  may  now  take  50  per  cent, 
of  the  sand  and  add  to  the  clay.  Upon  analysis  the  mixed 
soil  will  have  less  of  nutriment  than  the  clay  soil,  but  put 
them  both  in  cultivation,  and  it  will  be  found  that  the  mixed 
soil  will  be  the  most  fertile,  owing  to  the  fact,  that  there  is 
a  much  greater  surface  afforded  the  plants  than  before  for 
obtaining  the  nutritive  substances  of  the  soil. 

It  does  not  follow  by  any  means,  that  there  is  no  bene- 
fit derived  from  analysis.    On  the  contrary,  an  ultimate 


5^EW  METHOD  OF  SOIL  ANALYSIS. 


24Y 


analysis  of  a  soil,  together  with  its  soluble  matters  elimi- 
nated and  properly  characterized,  and  its  physical  qualities 
also  developed,  would  throw  much  light  upon  its  compara- 
tive fertility.  A  chemist  may  tell  a  soil  that  is  wholly 
barren,  by  the  absence  of  any  essential  constituent;  but 
where  all  are  present,  its  fertility  depends  upon  so  many 
contingencies  that  the  problem  becomes  very  difficult. 

221.  jVew  Method  of  So il  A n alysis, 

M.  Grandeau,  who  has  charge  of  one  of  the  experimental 
stations  in  France,  concludes  that  the  black  matter  which 
is  dissolved  out  of  the  humus  of  the  soil,  by  ammonia 
water,  contains  in  an  assimilable  form,  the  veritable  food 
of  plants. 

He  proposes  a  new  method  of  analysis  of  soils  to  deter- 
mine their  fertility,  founded  upon  the  actual  amount  of 
humus  in  them  in  combination  with  inorganic  matter, 
especially  lime.  He  gives  the  following  as  an  example  of 
his  method. 

He  took  two  soils,  one  known  to  be  fertile  without  ma- 
nure for  a  long  series  of  years,  and  the  other  only  equally 
fertile  with  the  application  of  10  tons  of  stable  manure 
to  the  acre.  The  ultimate  analysis  of  these  soils  gave  the 
following  results : 

1,000  parts  air-dry  son.  phoric    Potash.     Lime.   ^If^^'  Nitre. 

Matter.     ^^^^  sia. 

Naturally  fertile  soil...  71 .0. .  .2.00. . .  2.50. .  .5.20. .  .0.5  ..2.60 
I       Artificially  fertile  soil ..110.0...2.10...11.30...1.00...4.10..3.00 

Here  we  perceive  the  first,  or  fertile  soil,  has  less  organic 
matter,  less  phosphoric  acid  and  nitrogen,  and  much  less 
potash  and  magnesia.  And  only  in  the  lime  has  the  as- 
cendency. Any  chemist  would  have  pronounced  in  favor 
I      of  the  second  soil  as  being  the  most  fertile. 

M.  Grandeau,  struck  with  the  great  difierence  between 


248 


CHEMISTRY  OF  SOILS. 


the  two  soils  as  to  fertility,  and  the  failure  of  an  ultimate 
analysis  in  determining  that  difference,  instantly  set  about 
an  investigation  of  the  two  soils  in  a  more  philosoj)hical 
light.  He  established  another  method  of  analysis,  which 
was  crowned  with  success. 

This  analysis  was  founded  upon  the  assumption  that,  in 
its  wider  sense,  humus  is  a  combination  of  organic  and 
inorganic  matter,  that  it  contains  not  only  water  and  car-^ 
bon,  but  phosphoric  acid  and  potash,  and  all  the  other 
essential  elements  of  plant-food  in  soluble  conditions,  and 
that  the  minerals  tlius  associated  with  humus  or  in  humus, 
are  the  veritable  plant-food. 

His  analysis  of  the  two  soils  upon  this  method  gave  the 
following  results : 

No.  1.  NATrKx\LLY  Fertile  Soil,  from  Russia. 

1  000  r)art<s  Air-drv  Soil         Organic  Fixed  Phosplioric 

l,UUUpans  Airary  feoii.        Matter.  Ingredients.  Acid. 

Ultimate  analysis  71.0  868 . 1  2.0 

Grandeau's  method  20.4  21.6  1.7 

Plant-food,  undecomposed.  .50.6  846.5  0.3 

No.  2.  Artificially  Fertile  Soil,  from  France. 

1  nnn  ,.o«fo  A,-,.  ^r,r  c^ii  Organic  Fixed  Phosphoric 

1,000  parts  Air-dry  Soil.  Mmev.  Ingredients.  Acid. 

Ultimate  analysis  110.0  

Grandeau's  method   8.2  12.0  0.08 

Plant-food,  undecomposed.  .101.8  2.02 

In  this  table  the  naturally  fertile  soil  has  of  organic 
matter  20,4,  combined  with  21.6  of  fixed  ingredients,  and 
1.7  of  phosphoric  acid  ready  for  plant-food,  making  in 
the  agregate  43.7  in  1,000,  or  4.370  per  cent,  of  soluble 
food  for  plants.  While  the  other  soil  has  but  8.2  of 
organic  matter,  12.0  fixed  ingredients,  and  0.08  of  phos- 
phoric acid  in  a  condition  to  be  assimilated  by  plants, 
making  only  20.28  of  soluble  matters  or  2.028  per  cent. 

M.  Grandeau's   experiments  teach  further  that  the 


GKAXDEAU'S  EXPERIMENTS. 


249 


organic  or  combustible  portion  serves  only  as  the  vehicle 
for  the  assimilation  of  the  inorganic  portions.  That  just 
as  soon  as  the  sohition  of  humus  comes  in  contact  with  a 
vegetable  membrane,  a  separation  takes  place  between  the 
organic  and  inorganic  portions,  the  latter  being  taken  up 
as  plant-food,  and  the  former  left  in  the  soil.  While  this 
seems  to  confirm  Liebig's  mineral  theory,  that  the  true 
^lant-food  is  the  inorganic  compounds  in  the  soil,  it  also 
vindicates  the  humus  theory  in  part,  that  it  is  equally 
essential  in  the  assimilation  of  plant-food,  and  that  the 
amount  of  humus  in  a  soil  stands  in  a  direct  ratio  to  its 
fertility. 

222.  Deductions  f  rom  3L  GrandeaiC s  Experiments. 

The  experiments  of  M.  Grandeau  clearly  teach  one 
great  fact  not  particularly  mentioned  by  him.  That  the 
fertile  soil  has  a  large  proportion  of  soluble  phosphoric 
acid  ready  for  plant  use,  viz.  1.7  of  a  thousi  nd  parts  of 
air-dry  soil,  or  17  lbs.  for  every  10,000  lbs.  of  soil,  while 
the  non-fertile  soil  contains  only  -^-^  of  a  pound  for  that 
quantity  of  soil.  In  this  we  are  able  to  perceive  at  once, 
why  one  soil  is  so  much  more  fertile  than  the  other,  and  the 
reason  of  its  solubility  is  to  us  also  very  clear,  viz.  the 
carbonic  acid  which  emanates  from  the  decaying  vege- 
table matter  of  the  soil. 

We  would  add  two  more  propositions  to  M.  Grandeau's, 
as  deducible  from  these  experiments,  and  of  general  ap- 
plication :  first,  a  soil  is  fertile  according  to  the  amount 
of  soluble  phosphoric  acid  and  assimilable  nitrogen  in  it; 
and  second,  the  amount  of  soluble  phosphoric  acid  in  a 
soil  is  generally  according  to  the  amount  of  humus,  or 
decaying  vegetable  matter  in  that  soil. 

In  this  statement  we  do  not  intend  to  underrate  by 
any  means,  the  value  of  the  alkalies  and  alkaline  earths, 
and  other  fixed  ingredients,  as  food  for  plants,  but  only 
1 1-^^ 


250 


CHEMISTRY  OF  SOILS. 


to  show  that  phosphoric  acid,  being  the  sparsest  in  the 
soil,  and  the  most  difficult  of  assimilation,  is  the  most  im- 
portant in  an  economical  view.  But  more  of  this  wheir- 
we  come  specially  to  treat  of  this  acid. 

There  is  one  question  of  great  interest  connected  with 
M.  Grandeau's  investigations,  which  future  experiments 
will  have  to  determine.  Are  the  fixed  ingredients  asso- 
ciated with  organic  matter  in  its  enlarged  sense,  inherent 
in  the  vegetable  matter  itself  as  the  carbon  is,  or  are  they 
the  result  of  absorption  from  the  soil,  and  fertilizing  ele- 
ments applied  to  the  soil  ?  Or,  is  it  true,  while  the  humus 
retains  all  the  fixed  ingredients  inherent  in  itself,  it  has  the 
power  of  taking  up  and  entering  into  combination  with 
other  salts,  when  in  an  assimilable  condition  as  plant-food? 


CHAPTER  YII. 

NEW  MODE  OP  ANALYSIS  TESTED. — ORGANIC  MATTER  A 
MEANS  OF  SOLUBILITY.  SOLUBILITY  A  TEST  OF  FER- 
TILITY. 

223.  3L  Grandeau's  Theory  Tested. 

With  a  view  to  test  M.  Grandeau's  views  more  fully  as 
to  the  comparative  fertility  of  soils,  and  the  value  of  humus 
and  its  concomitants,  we  undertook  to  run  an  experiment 
in  1873,  Prof.  Shepard  the  younger,  of  Charleston,  agreeing 
to  give  an  analysis  of  the  soils  on  M.  Grandeau's  plan,  for 
the  benefit  of  science. 

We  selected  the  poorest  and  richest  spots  in  the  field, 
planting  rows  of  cotton  without  fertilizers  and  carefully 
noting  results.  The  rich  soil  made  at  the  rate  of  746  lbs. 
per  acre  of  seed  cotton.   The  poor  soil  only  247  lbs.  The 


GRAXDEAU'S  THEORY  TESTED. 


251 


analysis  of  these  two  soils  by  Dr.  W.  D.  Warner,  assistant 
of  Dr.  Shepard,  gave  the  following  results: 

Rich.  Poor, 
p.    c.         p.  c. 

Capillary  moisture,  i.  e.  expelled  on  air-drying  13.645  9.688 

Hygroscopic  moisture,  i.  e.  expelled  at  about  212*^  F.,  1.244  0.629 

Organic  matter  and  water  of  combination  expelled 

at  a  low  red-heat   4.326. ..  .2.440 

Fixed  ingredients  80.785. .  .87.243 

Total  100.000  100.000 

The  amount  of  nitrogen  in  the  thoroughly  air-dry  soils 
was  as  follows  : 

Rich  soil,  amount  of  nitrogen  0.102 

Equivalent  in  ammonia  (NH3)  0.125 

Poor  soil,  amount  of  nitrogen  0.065 

Equivalent  in  ammonia  0.079 

The  analyses  given  below  were  executed  on  the  plan 
proposed  by  M.  Grandeau.  In  1,000  grains  of  air-dry  soil 
were  found  : 

Rich.  Poor. 

Phosphoric  acid  0.154  0.106 

Sulphuric  acid  0.128  0.168 

Silicic  acid,  soluble  in  dilute  acids  0.292.  ..0.429 

Potash  0.022.... 0.025 

Soda  0.017.... 0.015 

Magnesia  0.352  0.584 

Lime  0.132  0.252 

Iron  oxide  and  alumina  0.840. . .  .0.252 

Total  determined  fixed  ingredients   1.937  1.700 

Fixed  ingredients,  undetermined  (largely 

silica)   0.043  0.420 

Organic  matter  13.047  7.763 

Total  humus  15.027. ..  .9.782 

This  is  a  remarkable  exposition  ;  and  while  we  are  not 
prepared  to  adopt  M.  Grandeau's  views,  in  toto,  we  believe 
that  he  has  made  a  decided  step  forward. 


252 


CHEMISTRY  OF  SOILS. 


Here  we  have,  out  of  1,000  lbs.  of  rich  soil,  15.027  of 
black  matter  (humus  in  its  widest  sense),  and  in  the  poor 
soil  9.782.  It  is  clear  that  outside  of  this,  all  is  insoluble 
and  unfit  for  plant-food,  i.  e.  in  its  present  form.  Of  the 
organic  matter,  nitrogen  is  admitted  to  be  the  most  essen- 
tial element:  the  only  one  in  fact  needed  to  be  supplied  to 
a  soil.  Of  this,  there  was  in  the  rich  soil  0.102,  in  the 
poor  soil  0.065  ;  showing  a  difference  of  57  per  cent,  of 
this  important  element  in  favor  of  the  rich  soil.  A  good 
portion  of  this  was  doubtless  in  the  form  of  ammonia  ; 
being  absorbed  and  held  by  the  organic  matter.  Of  the 
mineral  matter,  there  is  only  1.970  in  the  rich  soil,  and 
2.120  in  the  poor  soil,  found  in  the  humus.  Of  this,  0.43 
in  the  rich,  and  0.420  in  the  poor  is  undetermined,  but 
mostly  silica.  Ruling  out  iron  and  alumina  as  not  essen 
tial  for  plant  food,  only  in  the  merest  traces,  we  find  that 
the  poor  soil  has  more  available  plant-food  than  the  rich, 
viz.  as  1.448  is  to  1.097. 

The  four  important  mineral  substances,  silica,  magnesia, 
sulphuric  acid,  and  potash,  all  exist  more  abundantly  in  the 
poor  than  the  rich  soil,  while  lime  and  soda  have  only  a 
small  percentage  more  in  the  rich  than  in  the  poor.  Then  it 
is  certain  that  the  application  of  any  of  these  substances  to 
this  poor  soil,  would  not  increase  its  fertility  as  mere  food  ; 
possibly  they  might  act  chemically  on  the  organic  or  inor- 
ganic matter  in  the  soil,  in  preparing  more  soluble  food 
for  plants.  The  only  difference  then,  in  the  mineral  ele- 
ments, of  any  note,  is  in  the  phosphoric  acid,  there  being 
0.154  in  the  rich,  and  0.106  in  the  poor  soil.  Even  this 
would  be  less  available  in  a  poor  soil  than  a  rich  one,  as  it 
is  soluble  in  ammonia  and  not  in  water,  and  the  rich  soil 
would  have  more  ammonia  and  more  carbonic  acid  than 
a  poor  one,  to  aid  in  making  the  i^hosphoric  acid  soluble. 

It  is  remarkable  that  the  percentage  of  nitrogen  stands 
in  such  close  relation  to  that  of  the  organic  matter.  Thus 


ORGANIC  MATTER  A  MEANS  OF  SOLUBILITY. 


253 


in  tlie  rich  soil  the  organic  matter  is  64.96,  and  the  nitro- 
gen 35.04,  while  in  the  poor  soil  the  organic  matter  is  65.79 
per  cent.,  and  the  nitrogen  34.41.  Then  it  is  clear  that  the 
difference  between  the  two  soils  is  that  the  rich  has  more 
organic  matter  and  conseqnently  more  nitrogen,  and  also 
more  available  phosphoric  acid  than  the  poor. 

But  why  is  there  so  much  more  available  phosphoric 
acid  in  both  soils  than  there  is  potash,  which  is  demanded 
quite  as  much  as  plant-food?  The  principal  reason  is  that 
the  preliminary  treatment  of  the  soil. with  diluted  hydro- 
chloric acid,  in  order  to  extract  the  lim.e,  carries  off  more 
or  less  of  the  soluble  potash,  soda,  etc.,  while  the  phospho- 
ric acid  is  not  disturbed  by  it.  Again,  all  the  phosphoric 
acid  dissolved  by  the  ammonia  water  is  not  available  as 
plant-food,  but  only  so  much  of  it  as  would  be  soluble  in 
cold  water  (or  might  meet  Avith  other  solvents  in  the  soil), 
which  really  would  be  a  much  smaller  amount  than  indi- 
cated. Particularly  would  this  be  true  of  the  poor  soil, 
where  a  less  amount  of  ammonia  as  well  as  carbonic  acid 
Avould  be  found  to  aid  in  dissolving  the  phosphoric  acid. 

224.   Organic  Matter  a  3feans  of  Solubility. 

As  we  before  stated,  the  parts  of  a  soil  soluble  in  pure 
water  are  the  only  ones  that  can  be  now  appropriated  as 
plant-food.  Those  soluble  in  acids  may  be  brought  into 
requisition  during  the  season,  where  there  is  sufficient  or- 
ganic matter  to  produce  these  acids,  while  the  insoluble 
act  as  the  reserved  forces;  Avhich  by  further  weathering 
and  disintegration  may  (or  a  portion  of  them)  ultimately 
be  appropriated. 

Dr.  Anderson  found  upon  analysis  of  a  productive  wheat 
soil,  from  Renfrewshire,  Scotland,  that  it  contained  no 
phosphoric  aci(3  soluble  in  water,  at  least  none  that  he  could 
detect,  while  potassium  in  the  form  of  chloride  had  but 
0.0003,  and  yet  the  ash  of  wheat  is  said  to  contain  75  per 


254 


CHEMISTRY  OF  SOILS. 


cent,  of  these  two  substances.  Now  a  chemist  to  have 
taken  this  soil  without  knowing  its  fertility  would  have 
pronounced  it  a  poor  soil  for  wheat. 

In  the  same  soil  he  found  0.0469  of  potash,  and  0.0749 
of  phosphoric  acid  soluble  in  acids,  and  9.2471  of  organic 
matter.  The  productiveness  of  this  soil  then,  it  is  clear, 
lay  in  the  fact  that  there  was  a  sufficiency  of  these  elements 
soluble  in  acids,  and  a  sufficiency  of  organic  matter,  to 
evolve  carbonic  acid  in  the  soil,  which,  uniting  with  the 
rain  water,  kept  up  a  supply  of  soluble  food  for  a  large 
wheat  crop. 

Now  in  the  above  instance,  if  there  had  been  no  organic 
matter  in  the  soil,  the  percentage  of  phosphoric  acid  and 
potash  would  have  been  greater,  while  its  productive  power 
in  our  opinion  would  have  been  reduced  almost  to  barren- 
ness, as  far  as  the  wheat  crop  is  concerned,  from  the  lack 
of  agencies  in  the  soil  to  render  soluble  these  important 
principles  of  plant-food. 

225.  Solubility  a  Test  of  Fertility. 

The  quantity  of  soluble  matter  in  a  soil  is  always  a 
good  test  of  its  fertility.  In  the  productive  wheat  soil 
above  mentioned  there  was  soluble  in  water  and  acid 
per  cent,  of  the  soil,  about  half  of  which  was  the  peroxide 
of  iron.  In  a  sterile  soil  from  the  upper  Palatinate  of  Ba- 
varia was  soluble  in  acid  and  in  water,  about  half  being 
oxide  of  iron  and  alumina.  A  poor  sandy  soil  from  Bick- 
endorf,  analyzed  by  Grouven,  had  a  little  more  than  a 
half  per  cent,  of  soluble  matter  in  water,  while  a  rich  gar- 
den soil  from  Heidelburg,  liad  1.1 5G,  and  a  rich  clover  soil 
from  St.  Martin,  1.356. 

There  is  a  difference,  however,  in  the  amount  of  soluble 
matter  in  a  cultivated  soil,  having  more  in  the  spring  be- 
fore cropping,  and  less  in  the  fall  after  the  crop  has  been 
taken  off,  as  the  soluble  matter  of  the  soil  has  gone  to 


HUMUS  IX  SOILS. 


.255 


make  the  crops  which  have  grown  upon  it.  Thus  land 
at  rest  is  always  adding  to  its  stores  of  soluble  salts,  while 
that  which  is  cultivated  regularly  and  persistently,  is  al- 
ways losing  more  or  less  of  the  soluble  matters  according 
to  crops  grown  upon  it. 


CHAPTER  Yin. 

HUMUS  IX  SOILS. — HT7MIC  ACID. 

226.  Humus  in  Soils, 

Chemists  have  differed  much  upon  the  definition  of  the 
term  humus.  M.  Geo.  Ville  denominates  it  as  hydrO'Car- 
ban,  Liebig  defines  it  as  vegetable  matter  in  a  state  of 
decay ^  always  containing  ammonia  in  chemical  combina- 
tion. 

Both  of  them  are  right  doubtless.  For  while  we  are 
willing  to  admit  the  idea  that  humus  is  an  impure  hydro- 
carbon, we  are  equally  sure  that  it  seldom  progresses  to  a 
state  of  such  purity  as  that  it  is  relieved  of  all  the  mineral 
elements  naturally  inherent  in  it  which  would  constitute 
its  ash  if  burned.  And  we  are  equally  convinced  that  it 
imbibes  and  holds  ammonia  with  such  tenacity  as  to  al- 
ways have  it  in  chemical  combination. 

It  has  been  demonstrated  that  soils  abounding  in  humus 
will  increase  their  nitrogen  by  oxidation;  the  soil  losing 
some  of  its  carbon,  and  increasing  in  nitrogen,  which  must 
have  resulted  from  the  free  nitrogen  of  the  air.  (Boussin- 
gault.)    In  no  instance,  however,  have  soils  destitute  of 

I       organic  matter  been  found  to  increase  in  the  slightest 
degree  in  nitrogen. 

•  As  the  decay  of  Avoody  fibre  advances,  its  escaping 

carbon  converts  the  oxygen  of  the  surrounding  atmosphere 


256 


CHEMISTRY  OF  SOILS. 


into  carbonic  acid;  but  this  process  gradually  diminishes. 
When  it  ceases  entirely  the  remaining  j^roduct  is  vegetable 
mould  or  humus.  And  further  decay  may  take  place  by 
the  action  of  lime  or  ammonia. 

Humus  is  not  the  result  of  the  decay  of  pure  woody 
fibre  simply,  but  of  wood  Avith  all  of  its  constituents,  com- 
bustible and  incombustible.  Thus  in  its  evident  sense  it 
contains  probably  these  soluble  salts  intimately  associated 
with  the  insoluble  humus;  and  the  fertility  of  a  soil  depends 
not  so  much  on  the  quantity  of  organic  matter  in  it,  as 
the  extent  to  which  this  matter  is  combined  with  the  solu- 
ble inorganic  constituents  of  the  soil. 

Berzelius  contended  that  humus  was  a  direct  food  of 
plants,  and  liad  many  followers  in  Germany.  Liebig  op- 
posed this  view,  and  established  what  is  known  as  the 
mineral  theory.  He  contended  that  all  of  the  organic 
elements  of  the  soil  are  received  primarily  from  the  atmo- 
sphere; but  admitted  that  the  carbon  of  the  soil  might  be 
changed  into  another  form  than  humus,  and  appropriated 
as  plant-food. 

Humus  is  insoluble  while  undecomposed.  When  de- 
composed its  carbon  united  with  oxygen  may  be  taken  up 
by  water  as  carbonic  acid.  This  is  a  wise  provision,  as 
Liebig  himself  has  said,  for  if  it  was  wholly  soluble  in 
water,  the  heavy  rains  of  winter  would  greatly  impoverish 
our  soils. 

227.  Influence  of  Climate  on  Organic  Hatter  in  Soils, 

Organic  matter  abounds  much  more  in  northern  than 
in  southern  soils.  There  are  but  few  beds  of  peat  found 
in  the  South,  so  common  in  the  North.  This  is  mainly 
owing  to  the  heat  and  moisture,  which  carry  the  putrefac- 
tive stage  of  decomposition  to  a  much  farther  extent  in 
the  decay  of  vegetable  organisms,  in  a  warm  than  in  a 
cold  climate. 


IIUMIC  ACID. 


257 


The  benefit  of  liumus  also  in  southern  soils,  is  much 
more  marked  than  in  nortliern,  as  it  acids  coolness  and 
moisture  to  a  soil,  the  very  things  so  much  needed  in  the 
South.  And  as  cotton  culture  is  such  a  humus-destroying 
process,  it  renders  the  husbanding  of  this  invaluable  prin- 
ciple, as  perhaps  the  most  important  process  in  southern 
agriculture. 

228.  Hmnic  Acid. 

Humic  acid,  C^J1^^0y;^  +  ^l^.f},  may  be  obtained  by 
treating  black  humus  with  cai'bonate  of  soda,  which  sepa- 
rates it  into  humic  acid  and  humin.  The  same  result 
transpires  from  the  action  of  strong,  hot  hydrochloric  or 
sulphuric  acid  on  sugar,  starch,  and  cellulose.  (Mulder.) 

Alkalies  seem  to  develop  the  acid  character  both  of 
humic  and  ulmic  acids.  Those  portions  of  those  bodies 
which  are  acted  on  by  the  alkaline  carbonates  in  the  soil, 
or  by  carbonate  of  ammonia  brought  down  by  the  rains, 
are  properly  acids  and  have  solubility.  Nor  do  they  ap- 
pear to  exist  in  a  free  state,  but  in  combination  as  salts 
with  potash,  soda,  ammonia,  lime,  magnesia,  iron,  and 
alumina. 

The  humate  of  potash,  soda,  and  ammonia,  are  freely 
soluble  in  water.  All  the  other  humates,  as  above,  are 
either  insoluble,  or  but  slightly  soluble  in  water. 

From  soils  abounding  in  iron,  lime,  magnesia,  etc., 
especially  where  there  is  but  little  organic  matter,  w^ater 
removes  but  traces  of  the  humates  and  ulmates. 

But  in  soils  where  there  is  an  abundance  of  leaf  mould, 
as  in  gardens  and  peaty  soils,  where  not  only  humic  and 
ulmic  acid  abound,  but  also  carbonate  of  ammonia,  result- 
ing from  the  decay  of  nitrogenous  matters,  a  percepti- 
ble amount  of  the  humate  of  ammonia  is  abstracted  by 
water. 

There  also  appear  to  be  double  salts  of  these  acids,  in 
which  the  acid  is  combined  with  both  the  oxide  and  the 


258 


CIIEMISTKY  OF  SOILS. 


alkali.  These  double  salts  are  but  little  if  at  all  soluble 
in  water. 

Liebig  was  of  opinion  that  humic  acid  was  never 
formed  in  soils  containing  ordinary  amounts  of  vegetable 
matter,  or  if  found  under  such  circumstances,  it  could 
not  be  made  available  to  plant  growth,  as  both  the  cold 
of  winter  and  heat  of  summer  destroys  its  solubility. 
Hence  he  asserts  that  it  does  not  exist  in  the  humus  of 
vegetable  physiologists,  being  simply  a  product  of  the 
decomposition  of  humus  by  alkalies. 

Very  recently  Thenard  has  shown  that  humic  acid 
forms  with  ammonia  and  silica  very  permanent  acid  com- 
pounds, which  are  soluble  in  very  dilute  alkali,  from 
which  those  humates  cannot  be  separated  unchanged. 
They  suffer  a  loss  of  nitrogen  only  at  a  very  high  tem- 
perature. Nor  does  humic  acid  combine  with  silica  unless 
ammonia  be  present. 

It  has  previously  been  known  that  plants  grown  on 
soil  rich  in  silica  and  poor  in  humus,  contain  less  silica 
than  those  grown  on  soil  poor  in  silica  and  rich  in  humus. 
Since  an  excess  of  silica  exists  in  all  soils,  the  amount 
taken  up  by  a  plant,  very  clearly,  depends  on  other  circum- 
stances than  mere  quantity  existing  in  the  soil.  The  in- 
vestigations of  Thenard  have  thrown  much  light  on  this 
subject. 

We  have  now  the  best  reasons  for  believing  that  humic 
acid  performs  an  important  part  in  the  economy  of  plant 
g7*owth.  That  when  it  is  generated  in  a  soil,  it  unites 
with  silica  and  ammonia,  and  is  not  subject  to  the  adverse 
effect  of  heat  and  cold,  as  mentioned  by  Liebig. 

M.  Thenard  has  also  discovered  that  when  seeds  ger- 
minate on  wet  blotting  paper,  a  brown  zone  of  humus  is 
found  at  some  distance  from  the  seed,  Avhich  he  believes 
is  produced  by  the  action  of  the  atmosphere  on  some 
soluble,  colorless  body. 


PUTREFACTIOJ^. 


259 


CHAPTER  IZ. 

DECAY.  OEGANIC  MATTER  ESSENTIAL  TO  FERTILITY. 

229.  Decay, 

When  dead  plants  are  exposed  to  air  and  moisture  at 
common  temperatures,  they  lose  some  portion  of  their 
substance,  by  chemical  changes;  this  is  largely  due  to 
the  oxidation  of  a  portion  of  their  carbon  and  hydrogen. 
The  transition  from  a  moist  to  a  dry  state  often  repeated, 
hastens  this  decay. 

A  piece  of  wood  placed  in  water  where  atmospheric  air 
is  permitted  access  to  it,  will  remain  undecomposed  for  an 
indefinite  period.  The  same  effect  will  result  from  its 
being  placed  in  a  vacuum.  Ev^en  the  flesh  of  animals, 
so  prone  to  rapid  putrefaction,  will  remain  unchanged  for 
a  long  period  when  the  fluids  are  extracted  by  steam  or 
pressure. 

There  are  three  kinds  of  decay :  putrefaction,  erema- 
causis,  and  fermentation. 

230.  Putrefaction. 

Putrefaction  is  confined  to  animal  substances,  seeds,  etc., 
which  contain  albuminoids. 

When  albuminoids  decay  in  a  soil  abounding  in  organic 
matter,  the  following  chemical  changes  transpire  :  1.  The 
carbon  unites  with  oxygen,  forming  carbonic  acid,  a  part 
of  which  escapes  into  the  atmosphere.  2.  To  a  large 
extent  hydrogen  combines  with  oxygen,  forming  water. 
3.  The  nitrogen  unites  with  hydrogen,  yielding  ammonia, 
which  unites  also  Avith  carbon,  some  escaping  and  some 
combining  with  the  humus  of  the  soil.  The  more  humus 
in  a  soil,  the  more  ammonia  is  retained.  A  portion  of  nitro- 


260 


CHEMISTRY  OF  SOILS. 


gen  may  escape  in  a  free  state  where  there  is  an  excess 
of  oxygen.  Nitric  acid  is  never  formed  from  the  rapid 
putrefaction  of  animal  or  vegetable  substances.  4.  The 
sulphur  of  the  albuminoids  escapes  as  sulphuretted  hydro- 
gen gas,  but  may  be  retained  and  oxidized  into  sulphuric 
acid,  forming  sulphates. 

The  decay  of  nitrogenized  substances  passes  through 
complex  stages,  but  always  results  in  ammoniacal  salts. 
When  gluten  is  immersed  in  water  and  putrefies,  carbonic 
acid  and  pure  hydrogen  are  disengaged,  which  results  from 
the  decomposition  of  water.  Ammoniacal  salts  are  pro- 
duced at  the  same  time.  Ammonia  is  the  last  chemical 
result  from  the  putrefaction  of  animal  bodies.  While 
nitric  acid  results  from  the  decomposition  of  ammonia. 

231.  Eremacausis, 

Eremacausis,  which  means  slow  combustion,  is  con- 
fined to  vegetable  matters,  devoid  of  nitrogen,  and  abound- 
ing in  cellulose.  It  requires  an  excess  of  free  oxygen.  It 
operates  on  substances  difficult  of  separation,  as  stems, 
leaves,  etc. 

Vegetable  matter  is  mostly  composed  of  starch  and 
cellulose.  In  such  substances  decay  generally  takes  place 
slowly,  by  the  production  of  carbonic  acid  and  water. 
This  decomposition  proceeds  less  and  less  rapidly,  until 
all  the  carbon  and  hydrogen  become  oxidized,  or  as  hap- 
pens where  there  is  a  limited  access  of  air,  it  becomes 
checked  by  the  formation  of  substances,  which  are  ca- 
pable of  resisting  any  further  decomposition  under  ordi- 
nary circumstances,  as  humus.  This  is  manifest  in  the  fallen 
leaves  of  dense  forests,  and  peat  bogs ;  and  occurs  to  a 
less  extent  in  all  soils  containing  much  vegetable  matter. 

It  has  been  ascertained  by  chemical  examination  of 
the  escaping  gases,  that  the  hydrogen  of  wood  escapes 
more  rapidly  than  its  carbon,  so  that  humus  contains 


FEEMEXTATIOX. 


261 


more  carbon  than  the  vegetable  matter  from  which  it 
originated.  Marsh  gas  and  carbonic  oxide  gas  are  formed 
when  there  is  an  imperfect  access  of  air. 

232.  Ft rm entatioi i. 

Fermentation  acts  on  either  animal  or  vegetable  mat- 
ters, is  spontaneous,  involving  heat  and  a  rapid  evolution 
of  gas.  There  are  several  kinds  of  fermentation  :  vinous, 
acetic,  lactic,  etc.  All  three  of  these  processes  may  take 
place  at  once  in  a  mixture  of  cellulose,  albuminoids,  and 
sugar. 

While  eremecausis  requires  the  constant  presence  of  free 
oxygen^  ferment  at  io?i  may  go  on  in  the  absence  of  this  gas, 
by  an  organism  called  a  ferment.  The  yeast  fungus  {fo7'- 
vula  cerevisice)  produces  vinous  fermentation,  wliich  con- 
verts sugar  into  alcohol.  The  micoderraa  vini  facilitates 
acetous  fermentation,  by  which  alcohol  is  made  into  vine- 
gar. The  platinum  sponge  will  also  act  as  a  ferment  in 
acetification. 

PeniciUum  glaucurn  is  the  fungus  which,  it  is  believed, 
converts  sugar  into  lactic  acid,  rendering  milk  sour,  which 
is  the  first  stage  of  its  decomposition.  Starch  is  converted 
into  sugar  by  diastase^  which  acts  as  a  ferment  in  this  ease. 

There  are  doubtless  many  other  microscopic  fungi  which 
produce  decay  in  vegetable  products,  as  potato  rot,  mildew, 
blast  in  wheat,  etc. 

The  rotting  of  fruit,  according  to  Decaisne,  is  produced 
by  microscopic  fungi,  which  develop  in  moist,  confined 
air.  These  minute  germs  are  constantly  floating  in  the 
atmosphere,  which  attack  abraded  portions  of  the  surface, 
producing  rot.  Fruit,  even  when  bruised,  wrapped  in  cot- 
ton with  soft  tissue  paper,  or  with  waxed  paper  or  tin  foil, 
will  prevent  the  introduction  of  these  germs,  and  the  fruit 
is  thus  kept  for  a  long  time  without  change. 


262 


CHEMISTRY  OF  SOILS. 


233.    Organic  flatter  Essential  to  Fertility, 

The  theory  of  M.  Ville,  and  other  recent  chemists,  that 
chemical  manures  are  of  themselves  sufficient  to  produce 
the  most  abundant  crops  without  humus  in  a  soil,  seems  to 
have  been  elfectually  exploded  by  recent  investigations. 

In  fact,  M.  Ville  himself  shows  by  an  experiment  in  cal- 
cined sand,  that  without  manure  the  product  (of  wheat,  we 
suppose)  was  6;  with  his  complete  manure  of  potash,  Mme, 
phosphoric  acid,  and  nitrogen,  it  made  24;  without  phos- 
phate of  lime,  0  ;  with  humus,  32.  Thus  showing  that  the 
pot  with  humus  beat  that  without  25  per  cent. 

There  are  plants  which  will  grow  without  humus.  The 
cactus  has  its  home  in  the  most  arid  sands.  And  certain 
species  of  pines  and  firs  will  flourish  in  soils  comparatively 
destitute  of  humus,  owing  we  suppose  to  their  tap  roots, 
which  go  down  beyond  the  influence  of  the  burning  soil, 
and  take  up  soluble  matters  from  ever  moist  strata. 

Even  wheat  and  maize  have  been  made  to  grow  and 
produce  in  water  containing  all  the  nutritive  salts  in  solu- 
tion, but  this  does  not  prove  by  any  means  that  humus  is 
not  essential  in  a  normal  soil  for  the  proper  development 
of  agricultural  plants. 

During  the  present  year  (1874),  we  have  in  progress  an 
experiment  in  two  flower  pots,  both  planted  with  cotton 
seed.  In  the  one  there  is  no  soil  but  river  sand,  out  of 
which  all  the  soluble  matters  have  been  washed  in  shoally 
water;  in  •  the  other  there  is  half  sand  and  half  rotten 
mould  (a  poor  specimen  of  humus,  however).  To  the  soil 
in  both  of  the  flower  pots  has  been  added  an  equal  quan- 
tity of  all  the  soluble  salts  constituting  plant-food. 

In  the  one  without  Immus,  the  cotton  stalk  is  diminutive, 
yellowish,  and  sickly,  having  only  four  diminutive  forms 
for  fruit.  The  other  is  well  grown,  broad-leaved,  and  vigor- 
ous, has  twelve  forms,  and  requires  much  less  water  to 


BEXEFITS  OF  HUMUS. 


263 


prevent  wilting  of  the  leaves.  The  experiment  is  very 
conclusive  to  all  who  have  seen  it. 

But  though  organic  matter  is  a  necessary  concomitant 
of  all  fertile  soils,  they  are  not  necessarily  fertile  though 
abounding  in  it.  Especially  is  this  true  in  bottom  lands, 
and  in  colder  climates,  which  become  soured  by  an  over- 
plus of  this  very  principle  :  or  in  ferruginous  soils  which 
abound  in  bog-iron  ore,  before  referred  to  :  or  where,  from 
any  cause,  as  an  over-saturation  of  water  for  a  long  period, 
the  organic  matter  has  remained  in  an  insoluble  condition, 
and  has  not  combined  properly  with  the  inorganic  consti- 
tuents of  the  soil,  or  evolved  carbonic  acid  gas  in  sufficient 
quantities  to  dissolve  the  important  principles  of  jDlant- 
food. 

234.  Benefits  of  Humus, 

We  are  then  justified  in  the  following  conclusions  as  to 
the  beneficial  efi*ects  of  humus  or  organic  matter,  as  we  use 
these  terms  interchangably  to  a  large  extent,  although  ac- 
cording to  Liebig's  definition  there  is  but  little  difier- 
ence. 

1.  Humus  renders  stiff  soils  friable  and  open. 

2.  It  absorbs  moisture  from  the  atmosphere,  and  thus 
supplies  plants  with  it. 

3.  It  retains  the  moisture  longer  than  any  other  ingre- 
dient of  soils. 

4.  It  furnishes  a  considerable  portion  of  carbon  to 
plants,  either  directly  or  indirectly. 

5.  In  its  widest  sense,  it  supplies  the  mineral  elements 
of  decayed  matter  in  soluble  forms  for  plant-food. 

6.  It  absorbs  and  holds  free  ammonia  and  its  carbonate, 
and  thus  supplies  plants. 

7.  It  absorbs  lime,  and  its  carbonate,  and  renders  it 
assimilable  as  plant-food. 

8.  It  furnishes  a  solvent  to  the  soil  (carbonic  acid),  for 
the  silicate  of  potash  and  phosphate  of  lime,  by  which 


264 


CHEMISTRY  OF  SOILS. 


plants  are  supplied  with  the  two  important  compounds, 
phosphoric  acid  and  potash. 

9.  In  warm  climates,  it  cools  the  soil  by  the  constant 
imbibition  and  evaporation  of  moisture. 

10.  It  is,  in  fact,  a  prime  agent  in  the  laboratory  of  na- 
ture, for  carrying  on  chemical  changes  in  soils,  producing 
heat,  evolving  carbon,  oxygen,  and  hydrogen,  as  well  as 
nitrogen  obtained  by  absorption. 

Perhaps  of  all  of  the  benefits  resulting  from  humus  in 
the  soil,  this  last  is  the  most  important. 

Each  and  every  one  of  these  effects  have  been  again  and 
again  demonstrated  by  the  author  and  others,  not  in  flower 
pots  simply,  but  in  the  open  fields,  and  yet  we  find  men 
assuming  to  be  agricultural  chemists  who  consider  humus 
in  a  soil  of  no  agricultural  value. 


PAET  YIL 
FERTILIZERS  AND  NATURAL  MANURES. 


CHAPTER  I. 

INTRODUCTIOIS^.  SPECIAL  FERTILIZEES.  NITROGEN  AS  A 

FEPvTILIZER.  ITS  DIFFERENT  FORMS. 

235.   The  Subject  Introduced, 

The  most  difficult  and  yet  the  most  important  part  of 
agriculture  is  that  which  relates  to  the  restoration  of  soils 
by  the  application  of  manurial  substances.  Much  has  been 
learned  empirically,  and  science  has  aided  in  the  develop- 
ment of  a  number  of  interesting  truths;  but  when  it  is 
known  that  everything  truly  valuable  in  agricultural  sci- 
ence must  be  learned  by  the  slow  processes  of  the  induc- 
tive philosophy,  and  the  facts  thus  brought  out  are  depend- 
ent on  so  many  contingencies,  as  to  soil,  temperature, 
seasons,  climate,  the  character  of  the  fertilizer,  and  the 
plant  itself,  we  feel  how  little  has  been  learned  thus  far, 
and  how  much  of  that  will  have  to  be  unlearned  in  the 
further  progress  of  the  science. 

In  this  department,  so  intricate  and  so  important,  we 
claim  to  have  added  something  to  the  advancement  of 
agricultural  science  ;  as  will  be  seen  from  the  numerous 
experiments  made,  and  the  deductions  which  naturally 
result  from  them.  We  will  be  jDardoned  then  for  the  space 
taken  up  by  these  experiments,  as  all  well-informed  minds 
must  admit  them  to  be  much  more  valuable  as  contribu- 
12 


266 


FERTILIZERS  AND  NATURAL  MANURES. 


tions  to  science,  than  the  most  plausible  theories  based 
upon  mere  speculation. 

236.  Fertilizers^  How  Divided. 

Fertilizers  or  manures  are  properly  divided  into  two 
great  classes,  natural  and  artificial. 

These  may  be  again  divided  into  those  which  supply 
food  to  the  plant,  and  those  which  prepare  food  for  the 
plant.  It  is  important  to  keep  up  this  distinction  in  all 
our  investigations  of  this  important  subject. 

To  the  first  class,  as  regards  our  wornout  lands,  we 
may  put  down  as  always  essential,  nitrogen  and  phosphoric 
acid;  as  often  needed,  potash  and  sulphuric  acid;  as  occa- 
sionally useful,  magnesia,  lime,  chlorine,  and  soda;  as  never 
needed,  silica,  alumina,  and  iron. 

To  the  second  class  belong  the  caustic  alkalies  and 
alkaline  earths,  lime,  potash  and  soda,  sulphuric  and  car- 
bonic acid,  ammonia  and  chloride  of  sodium. 

In  order  for  the  greatest  possible  benefit,  fertilizers 
should  be  applied  previous  to  planting  the  seed,  as  the 
good  to  be  accomplished  by  them  is  mainly  in  the  vigor- 
ous starting  of  the  plant,  the  early  roots  being  much  more 
susceptible  of  their  action  than  the  later  roots,  and  having 
as  well,  a  more  decided  influence  on  the  nutrition  of  the 
plant. 

237.  Special  Fertilizers, 

Agricultural  chemistry  at  first  taught  that  a  perfect 
manure  must  have  all  the  elements  of  plants  in  it,  not  esti- 
mating the  value  of  special  fertilizers  as  it  now  does. 
Ashes  and  stable  manure  fulfilled  these  indications. 

But  when  Peruvian  guano  was  found  by  experiment  to 
be  the  most  powerful  fertilizer  known,  and  its  analysis 
showed  it  to  be  an  ammoniated  phosphate,  with  a  little 
potash,  common  salt,  and  silica,  the  attention  of  the  agri- 


SPECIAL  FEraiLIZEKS. 


267 


cultural  world  was  at  once  directed  to  ammouia  and  phos- 
phoric acid  as  special  fertilizers  needed  for  worn  soils. 

Now  what  is  the  rationale  of  the  action  of  these  two 
substances  in  producing  such  powerful  eftects  upon  all 
plants  and  nearly  all  soils?  Why  is  not  silica  a  good 
fertilizer  as  well,  since  it  supplies  some  plants  with  a  max- 
imum amount  of  food  ?  The  answer  is  easily  given.  Ma- 
ture has  provided  inexhaustible  stores  of  it  in  all  soils,  and 
plants  can  get  enough  of  it,  without  having  to  wait  for  its 
reapplication. 

The  same  is  true  of  oxygen  and  hydrogen,  both  as  soil 
and  atmospheric  food,  and  of  carbon  to  all  plants  which  are 
supplied  with  this  element  from  the  atmosphere. 

Of  the  four  organic  elements,  then,  it  is  only  necessary 
to  apply  nitrogen  to  most  soils  as  a  fertilizer. 

Of  the  ten  essential  mineral  constituents  of  plants,  it 
may  be  safely  announced  that  iron  and  silica  are  never 
needed  to  be  applied  as  fertilizers;  that  soils  which  do 
not  contain  them  in  sufficient  quantities  in  soluble  propor- 
tions are  not  worth  the  expense  of  renovation. 

Ruling  out  iodine  as  confined  to  marine  plants,  and 
manganese  and  alumina  as  accidental,  and  not  important 
to  vegetable  growth,  we  have  the  seven  remaining  ingre- 
dients, all  of  which,  under  certain  circumstances,  and  in 
certain  soils,  may  be  economically  applied  as  fertilizers. 

Nitrogen  of  the  atmospheric  and  phosphorus  of  the  tel- 
luric, are  the  most  important  elements  in  all  fertilizers  for 
our  plants  and  soils.  The  former  is  always  taken  up  as  am- 
monia or  nitric  acid  with  a  base,  the  latter  as  phosphoric 
acid. 

Different  manures  have  different  effects  on  plants. 
Thus,  jDurely  mineral  manures  have  but  little  effect  on  the 
grasses,  but  produce  a  marked  improvement  on  the  clovers, 
as  determined  on  the  experimental  ground  at  Chiswick, 
England.     Solutions  of  ammonia  salts  with  nitrate  of 


268 


FERTILIZERS  AND  NATURAL  MANURES. 


soda  resulted  differently  on  almost  all  the  different  sjDecies 
of  plants ;  and  it  was  found  that  a  plant  acted  upon  favor- 
ably by  one  of  these  groups  of  salts,  was  influenced  in  quite 
the  opposite  manner  by  the  other. 

238.  Hjffect  of  Fertilizers  in  Hastening  Maturity, 

The  impetus  given  to  cotton  plants  in  the  early  stage, 
and  consequent  hastening  of  the  time  of  maturity,  is  per- 
haps the  greatest  benefit  of  fertilizers.  This  applies  par- 
ticularly to  the  northern  section  of  the  cotton  belt.  The 
following  experiment  will  illustrate  this  fact: 

In  1870,  we  aj)plied  at  the  rate  of  300  lbs.  per  acre  of 
amnioniated  phosphate  to  three  rows  of  cotton,  70  yards 
long,  and  by  their  side  three  rows  not  manured,  counting 
only  the  middle  rows.  They  produced  as  follows,  the 
dates  representing  the  different  pickings: 

Sept.  15.     Sept.  24.     Oct.  14.      Dec.  14.       Total.  "^^^cre*'^ 

Fertilized  45  oz. . .  .156  oz. . .  .87  oz. . . .  6  oz. . .  .287  oz  . . .  .1076 

Not  fertilized.  1   21  "  61  *^  35  "...  .118  "   436 

This  year,  the  first  killing  frost  was  early  in  December, 
which  greatly  favored  the  row  not  fertilized. 

In  this  experiment,  cotton  planted  24th  of  April,  ma- 
nured with  $10  worth  of  amnioniated  phosphate,  produced 
in  five  months,  at  the  second  picking  on  the  24th  Sept.,  201 
oz.  in  rows  of  70  yards,  equal  to  753  lbs.  per  acre;  while 
the  natural  soil  produced  only  22  oz.,  equal  to  82  lbs.  per 
acre — being  an  increased  product  of  671  lbs.;  the  lint  of 
which,  to  say  nothing  of  the  value  of  the  seed,  would  bring 
$33.60,  at  15c.  per  lb.,  leaving  $123.60  clear  profit  per 
acre,  after  paying  for  the  fertilizer. 

The  introduction  of  concentrated  fertilizers  has  ex- 
tended the  cotton  belt  at  least  one  degree  northward  of  the 
true  isothermal  line  heretofore  considered  the  mark  beyond 
which  it  ceased  to  be  profitable.    Then  a  climate  that  gives 


FORMS  IN  WHICH  NITROGEN  ENTERS  PLANTS.  269 


a  good  warm  soil  and  atmosphere  for  five  months,  will  pro- 
duce cotton  profitably  by  their  aid.  The  same  climate 
without  them,  would  require  six  months  or  more. 

239.  Nitrogen  as  a  Fertilizer, 

The  importance  of  nitrogen  as  a  fertilizer  has  been  well 
demonstrated  by  the  author  in  a  number  of  experiments ; 
from  which  we  are  satisfied  of  the  truth  of  the  following 
propositions:  1.  That  nitrogen  is  the  only  organic  element 
exhausted  from  soils,  and  needed  as  a  fertilizer.  2.  That 
ammonia  is  the  quickest  and  most  powerful  of  all  the  ni- 
trogenous fertilizers.  3.  That  nitrogen  in  an  organic  state 
as  albuminoids  is  the  next  best,  being  converted  rapidly 
into  ammonia  by  putrefactive  decay.  4.  That  nitric  acid 
in  the  nitrates  is  less  active  and  efficient  than  either  of  the 
three. 

These  views  run  in  the  teeth  of  experiments  by  a  num- 
ber of  scientists;  but  ours  were  made  on  worn  soils  with 
natural  surroundings;  theirs,  in  an  abnormal  media,  and 
could  not  produce  practical  results. 

240.  Forms  in  which  Nitrogen  enters  Plants, 

It  is  the  opinion  of  some  chemists  that  nitrogen,  to  be 
available  as  plant-food,  whether  free  or  in  the  form  of  am- 
monia, has  first  to  be  converted  into  nitric  acid. 

While  it  may  be  true  that  nitric  acid,  uniting  with  cer- 
tain bases  in  the  soil,  constitutes  an  important  part  of  the 
nitrogenous  food  of  plants,  we  have  no  doubt  that  ammonia 
without  undergoing  nitrification,  is  also  taken  up  by  plants 
as  food. 

Liebig  was  of  the  opinion  that  ammonia  is  the  only 
form  in  which  nitrogen  enters  plants.  Others  have  sup- 
posed that  urea  and  hippuric  acid  are  also  assimilated  by 
plants,  but  it  is  most  probable  that  they  are  first  converted 
into  ammonia  or  nitric  acid. 


270 


FEETILIZERS  AND  NATUKAL  MANURES. 


When  albuminoids  (as  dried  flesh)  are  placed  in  the 
soil  as  a  fertilizer,  the  first  process  with  the  nitrogen  is  the 
formation  of  ammonia,  under  putrefactive  decay.  That  it 
acts  at  once  as  a  fertilizer,  and  is  taken  up  as  ammonia,  we 
have  no  doubt.  That  some  of  the  ammonia  is  converted 
into  nitric  acid,  and  this  again  into  nitrates,  is  also  proba- 
bly true.  But  this  could  only  proceed  under  a  slow  decay, 
and  if  the  nitric  acid  should  not  find  a  base  with  which  to 
unite  when  formed,  it  would  act  as  a  powerful  corrosive 
poison,  and  retard  rather  than  improve  vegetation. 

241.  Ammonia  and  Nitric  Acid  in  Plants, 

While  it  is  probably  true  that  most  of  the  ammonia  and 
nitric  acid  taken  up  by  plants  is  changed,  leaving  organic 
nitrogen  in  their  structure,  yet  both  of  th(?se  compounds 
are  known  to  exist  free  to  a  certain  extent  in  plants. 

Liebig  found  ammonia  in  the  juices  of  beet  root,  birch 
and  maple  trees,  associated  with  cane  sugar.  It  also  com- 
bines with  acid  substances  in  tobacco  plants,  scurvy  grass, 
elder  flowers,  and  many  fungi.  This  can  easily  be  detected 
by  mixing  their  juices  with  quicklime.  Ammonia  is 
actually  perspired  by  the  Chenipodium  olidum  (stinking 
goosefoot),  and  some  sweet-smelling  plants  and  flowers. 

Nearly  all  vegetable  substances  yield  ammonia  by  dis- 
tillation, and  traces  are  found  in  most  vegetable  extracts.  % 
When  wood  is  distilled  for  the  manufacture  of  pyroligne- 
ous  acid,  ammonia  is  given  ofi*.  It  is  probable  that  some 
of  the  ammonia  of  plants  remains  unchanged  as  imbibed 
by  the  roots,  some  is  formed  by  transposition  within  the 
plant,  and  some  in  the  process  of  extraction. 

Nitric  acid  is  also  found  in  many  known  plants  com- 
bined with  potash,  soda,  lime,  and  magnesia;  as  the  nettle, 
sunflower,  tobacco,  and  also  in  grains  of  barley. 

The  nitrates  and  ammonia  being  both  found  in  plants, 
and  very  soluble,  and  at  the  same  time  powerful  fertilizers. 


NITRIFICATION. 


271 


it  is  very  reasonable  to  infer  that  they  are  taken  up  directly 
as  plant-food. 

242.  Amount  of  Nitroge'iv  Required  hy  Crops. 

From  experiments  recently  made,  Ritthausen  concludes 
that  an  increase  in  the  nitrogen  of  the  fertilizer,  applied 
to  plants,  will  produce  an  increase  in  the  percentage  of 
nitrogen  in  the  plant  as  a  whole,  and  in  its  different  parts. 

Hermstadt  found,  on  the  application  of  different  ma- 
nures, that  gluten  was  increased  in  wheat  according  to  the 
amount  of  ammonia  evolved.  Thus  without  manure,  the 
wheat  contained  9.2  of  gluten,  cow  dung  12,  horse  dung 
13.7,  night  soil  33.14,  and  dried  human  urine  35.1  per 
cent. 

Hellriegel  estimated  from  experiments  made  by  him 
that  70  lbs.  of  assimilable  nitrogen  is  sufficient  to  pro- 
duce a  maximum  crop  of  wheat  in  1,000,000  lbs.  of  soil, 
while  63  lbs.  would  be  sufficient  for  rye,  and  53  for  oats. 
Common  arable  soil  the  depth  of  one  foot,  will  weigh  about 
4,000,000  lbs.  per  acre,  then  252  lbs.  of  nitrogen,  in  the 
form  of  ammonia  and  nitric  acid,  will  produce  as  much 
wheat  as  any  amount  above  that. 


CHAPTER  II. 

NITRIFICATION.  —  CONDITIONS  ESSENTIAL  TO  IT.  IMPOR- 
TANCE or  NITRIC  ACID  AS  A  FERTILIZER. 

243.  Nitrification. 

Nitrification  is  the  process  by  w^hich  nitric  acid  is 
formed  in  the  atmosphere  or  in  the  soiL 

This  is  a  very  constant  result  in  every  soil,  wherever 
ammonia  is  exposed  to  the  action  of  oxygen. 


272 


FERTILILERS  AND  NATURAL  MANURES. 


Nitric  acid  does  not  remain  free  in  soils,  however,  but 
unites  with  alkalies,  metals,  and  alkaline  earths,  some  of 
them  soluble  and  some  insoluble.  Thus,  the  nitrate  of  iron 
in  one  form  being  an  insoluble  compound,  the  nitrogen  is 
locked  up  and  unavailable  ;  while  the  nitrates  of  potash, 
soda,  and  magnesia  may  be  made  available  as  plant-food. 
The  nitrate  of  lime  always  accompanies  the  nitrate  of 
potash  in  artificial  nitre  beds. 

This  process  of  nitrification  is  much  more  rapid  in  the 
tropics  than  in  the  temperate  zones,  and  in  hot  weather 
than  cold. 

In  Bengal  and  other  tropical  regions,  incrustations  of 
nitrate  of  potash  are  often  seen  during  dry  weather, 
formed  on  the  surface  of  the  earth  by  capillary  attraction. 
Similar  incrustations  of  other  salts,  as  sulphur,  magnesia, 
and  soda,  we  have  observed  rising  to  the  surface  from  fer- 
tilizers applied  six  or  eight  inches  deep  in  the  soil,  during 
spells  of  dry  w^eather. 

Drought  always  eliminates  nitrous  particles  in  a  soil, 
while  rain  leaches  them  out,  but  aids  their  formation  in 
the  right  quantity  and  time  ;  constant  rain,  however, 
prevents  the  formation  of  nitre. 

Boussingault  found  in  a  garden  soil  after  fourteen 
days  of  hot,  dry  weather  (estimating  one  foot  in  depth), 
at  the  rate  of  911  pounds  of  nitrate  of  potash  per  acre. 
It  then  rained  every  day  for  twenty  days,  when  an  analy- 
sis revealed  38  pounds.  In  the  same  soil,  after  rain  in 
September,  and  tw^o  weeks  of  hot,  dry  weather,  the  first 
of  October  it  had  increased  to  1,290  pounds  per  acre. 

Cloez  produced  nitre  in  abundance  by  causing  an 
atmosphere  purified  from  ammonia  and  nitric  acid  to  pass 
through  a  vessel  charged  with  solution  of  carbonate  of 
potassa  and  filled  with  washed  soil.  The  same  soil  cal- 
cined and  deprived  of  organic  matter,  had  but  a  trace, 
showing  very  clearly  the  influence  of  humus  in  nitrification. 


CONDITIONS  ESSENTIAL  TO  NITRIFICATION. 


273 


Prof.  Johnson  is  of  opinion  that  the  nitrogen  con- 
tained in  the  interstices  of  the  soil  is  directly  oxidized  to 
nitric  acid  by  ozone  generated  from  the  oxygen  of  organic 
matter.  This  idea  is  strengthened  from  the  fact  estab- 
lished by  Reichardt  and  Blumtritt,  that  humus  condenses 
atmospheric  nitrogen  in  its  pores. 

Ammonia  is  always  formed,  nitric  acid  never,  when 
moist  azotized  substances  are  exposed  to  air.  When 
alkalies  are  present,  however,  a  union  of  oxygen  and 
nitrogen  takes  place  and  nitrates  are  formed.  (Liebig.)  A 
large  excess  of  hydrogen  must  be  present  either  in  a  state 
of  oxidation  or  combustion  for  nitric  acid  to  be  formed. 

M.  Schloesing,  Avho  has  experimented  much  on  the 
value  of  nitrogen,  and  formation  of  nitrates  in  soils,  con- 
chides  that  the  slow  combustion  of  organic  matter  in 
soils,  is  almost  independent  of  the  amount  of  oxygen  in 
the  confined  air.  That  the  temperature  has  much  to  do 
with  nitrification  and  the  formation  of  carbonic  acid. 
Thus  at  an  average  of  75^  F.  twice  as  much  carbonic  acid 
was  formed  as  when  the  average  was  only  60^. 

The  amount  of  nitric  acid  formed  varied  with  the 
amount  of  moisture,  a  dry  soil  being  more  variable  than 
a  moist  soil.  In  a  nearly  dry  soil,  the  nitric  acid  varied 
from  95.7  to  246.6  milligrammes  in  a  kilogram  of  earth. 
In  earth  having  24  per  cent,  of  moisture,  the  production 
varied  from  199  to  225  milligrammes  of  nitric  acid  in  the 
same  quantity  of  earth. 

244.'  Conditions  Essential  to  Nitrification, 

Conditions  essential  to  nitrification  are  hot  weather, 
moisture,  and  an  alkali  base,  as  potash,  soda,  or  lime.  Con- 
tinued moisture,  however,  would  defeat  it.  Moisture,  after 
hot,  dry  weather,  is  the  most  favorable  condition. 

The  presence  of  water  is  essential  to  nitrification,  since 
nitric  acid  cannot  be  formed  without  it. 
12* 


274 


FERTILIZEES  AND  NATUKAL  MANURES. 


Boussingault  found  caustie  lime  opposed  nitrification 
by  its  disposition  to  generate  ammonia  in  the  soil.  He 
found  that  850  grammes  of  sand  mixed  with  1,000  grammes 
of  soil,  acquired  482  grammes  of  nitric  acid,  and  .012  of 
ammonia,  while  200  grammes  of  quick  lime  with  the  same 
soil  acquired  only  .099  grammes  of  nitric  acid,  and  .303 
grammes  of  ammonia.  The  action  of  the  sand  was  pro- 
bably owing  to  the  division  of  the  soil,  and  greater  exposure 
of  surface  to  the  atmosphere.  On  the  same  principle 
ploughing  aids  nitrification,  and  tends  to  fertilize  the  soil. 

Although  artificial  nitre  beds  have  been  in  vogue  for 
near  a  century,  their  processes  have  been  rather  empirical 
than  scientific.  This  much,  however,  is  known  :  animal  or 
vegetable  substances  containing  nitrogen,  are  essential  in 
a  soil,  and  when  they  disappear  by  decay  produced  by  the 
moistening  and  drying  process,  particularly  in  hot  weather, 
nitric  acid  is  formed. 

Prof.  Johnson  is  of  the  opinion  that  nitric  acid  is 
formed  during  the  process  of  the  oxidation  of  organic  mat- 
ter in  the  soil,  with  free  nitrogen,  when  oxygen  is  in  excess 
and  the  decay  not  too  rapid. 

This,  if  it  proves  to  be  an  established  fact,  will  consti- 
tute another  reason  why  organic  matter  is  so  important  a 
principle  in  all  fertile  soils ;  and  it  is  highly  probable  that 
the  value  of  vegetable  decay  in  a  soil,  is  owing  largely  to 
nitrification.  The  nitrogen  being  united  with  the  oxygen 
as  decay  takes  place,  and  thus  nitric  acid  is  formed. 

245.  Ammonia  a  Principal  Source  of  Nitric  Acid, 

As  the  nitrogen  of  azotized  bodies  always  assumes  the 
form  of  ammonia,  which  unites  with  oxygen  more  readily 
than  any  other  of  its  compounds,  we  cannot  doubt  that 
ammonia  is  the  principal  source  of  nitric  acid  on  the  sur- 
face of  the  earth.  (Liebig.) 

The  sulphates  and  sulphurets  doubtless  gather  and  im- 


IMPOKTAXCE  OF  XITHIC  ACID  AS  A  FEKTILIZER.  275 


part  oxygen  to  oxidizable  substances  in  the  same  way. 
Thus  ammonia  is  convertible  into  nitric  acid  in  the  soil, 
and  made  perhaps  more  available  as  plant-food.  There  is 
a  strong  disposition  for  the  nitrogen  of  ammonia  to  be  thus 
transposed. 

Nitric  acid  is  rarely  generated  from  ammonia,  however, 
in  the  absence  of  all  matter  capable  of  eremacausis.  Thus 
when  azotized  substances  are  burned,  their  nitrogen  does 
not  combine  with  oxygen,  as  the  carbon  and  hydrogen 
have  a  stronger  affinity  for  it. 

Ammonia  cannot  be  exposed  to  oxygen,  without  form- 
ing nitric  acid,  while  other  nitrogenous  compounds  act 
differently. 

During  the  combustion  of  ammonia,  water  and  nitric 
acid  are  both  formed. 

M.  Schloesing  found  that  not  one-fifth  of  the  ammonia 
Avas  formed  in  the  reduction  of  the  nitrates,  which  might 
have  been  from  the  amount  of  nitrogen  in  the  nitrates. 
He  concludes  that  there  is  always  a  loss  of  nitrogen  in  the 
decomposition  of  organic  matter  from  whatever  cause. 

246.  Importance  of  Nitric  Acid  as  a  Fertilizer, 

The  importance  of  nitric  acid  as  a  fertilizer  is  thus  de- 
monstrated by  Boussingault:  Three  pots.  A,  C,  and  D,  were 
filled  with  pounded  brick-dust  and  sand,  and  two  seeds  of 
dwarf  sunflower  planted  in  each,  and  watered  with  distilled 
water  as  needed.  C  and  D  had  phosphate  of  lime,  clover 
ashes,  and  bi-carbonate  of  potash  added  to  them.  D  had 
also  1.4  grammes  of  nitrate  of  potash.  The  actual  weight 
of  the  dry  crop  (the  seed  being  1)  was,  A,  3.6;  C,  4.6;  D, 
198.3.  The  amount  of  nitrogen  acquired  in  86  days  of 
vegetation  was.  A,  .0023;  C,  .0027;  D,  .1666.  So  that  the 
nitrogen  applied  to  the  soil  produced  43  times  more  than 
that  in  which  every  other  ingredient  was  present. 

This  experiment  teaches  that  while  a  small  amount  of 


276 


FEETILIZERS  AND  NATURAL  MANURES. 


nitrogen  may  be  imbibed  from  the  air,  possibly  as  ammonia, 
it  must  exist  in  the  soil  to  produce  crops ;  that  nitric 
acid  of  itself  can  furnish  a  supply  of  nitrogen  to  plants ; 
and  the  inference  is,  that  even  that  supplied  by  the  atmo- 
sphere, was  first  held  in  the  interstices  of  the  soil  and 
converted  into  nitric  acid. 

In  another  experiment  with  nitrate  of  soda  in  four 
pots,  the  first  receiving  no  nitrogen  except  what  was  in 
the  seed,  IsTo.  3  twice  as  much  as  No.  2,  and  No.  4  three 
times  as  much  as  No.  3  ;  the  first  pot  produced  1,  the 
second  1.8,  the  third  2.8,  and  the  fourth  8.5. 

These  experiments  show  conclusively  the  value  of 
nitric  acid  as  a  fertilizer;  but  do  not  warrant  the  con- 
clusion of  Prof.  Johnson  that  ammonia  as  naturally  sup- 
plied^  is  of  trifling  importance  to  vegetation,  and  the 
nitrates  are  the  chief  means  of  furnishing  crops  with 
nitrogen.  Of  the  two  we  are  satisfied  that  ammonia  is  the 
most  powerful  fertilizer,  and  that  either  directly  or  through 
nitric  acid,  it  furnishes  the  great  bulk  of  nitrogen  to  all 
agricultural  crops. 


CHAPTER  III. 

AMMONIA. 

247.  Formation  of  Ammonia  in  Soils, 

Ammonia  is  formed  in  the  soil  from  the  decomposition 
of  the  albuminoids  in  the  decay  of  both  animal  and  vegeta- 
ble substances,  as  well  as  from  the  reduction  of  the  nitrates. 

Faraday  has  demonstrated  that  ammonia  exists  in  all 
porous  bodies  exposed  to  the  air  in  minute  quantities. 

In  nine  experiments  on  wheat,  barley,  etc.,  by  Gilbert 
Lawes  and  Pugh,  mixed  with  soil  and  exposed  to  cur- 


ESCAPE  OF  AMMONIA  FEOM  SOILS. 


277 


rents  of  air  for  six  months  in  various  conditions  of  mois- 
ture, they  found  from  11  to  58  per  cent,  of  nitrogen  was 
converted  into  ammonia,  about  4  per  cent,  only  escaping. 

The  ammonia  also  of  a  soil  is  frequently  converted 
into  nitric  acid,  by  oxidation  of  sesqui-oxide  of  iron. 
This  compound  is  constantly  yielding  oxygen  to  the  soil ; 
while  the  protoxide  is  absorbing  oxygen  from  the  air  and 
passing  into  the  sesqui-oxide  of  iron.  Thus  a  supply  of 
atmospheric  oxygen  is  furnished  substances  which  cannot 
obtain  it  otherwise. 

While  in  most  cases  organic  matter  (humus)  is  a  source 
of  nitric  acid,  in  compact  soils  some  distance  from  the 
surface  their  hydrogen  and  carbon  may  take  oxygen  from 
the  nitric  acid  already  formed,  converting  the  nitrogen 
into  ammonia.  Pelouze  proves  this  by  experiments  with 
putrefying  animal  substances. 

The  assimilable  nitrogen  of  a  soil,  consists  of  the  am- 
monia and  the  nitric  acid.  The  unassimilable,  is  the 
nitrogen  in  the  organic  matter,  and  the  free  nitrogen  in 
the  interstices  of  the  soil.  The  conversion  of  nitric  acid 
into  ammonia  in  compact  soils,  renders  it  comparatively 
free  from  leaching,  as  humus  and  clay  will  hold  it  with 
great  tenacity. 

Schonbein  found  that  the  white  fumes  emitted  by 
moist  phosphorus  are  nitrate  of  ammonia,  instead  of  phos- 
phoric acid.  He  supposed  that  the  nitrogen  of  the  air,  by 
induction,  combines  with  three  equivalents  of  water,  and 
nitrous  acid  and  ammonia  are  both  formed.  This  salt  is 
generated  just  from  opposite  conditions  supposed  to  pro- 
duce it,  and  how  much  may  thus  be  formed  in  nature,  no 
one  knows. 

248.  Escape  of  A7nmo7iia  from  Soils. 

The  clear  inference  from  experiments  made  by  Brust- 
lieu,  is  that  soils  do  not  retain  ammonia  long  near  their 


278  FERTILIZEES  AND  NATURAL  MANURES. 


surface  ;  and  that  fertilizers  containing  ammonia  should 
be  placed  deep  in  the  soil,  and  as  late  as  possible  in  the 
spring,  just  before  the  seed  is  deposited  in  the  ground. 

Brustlieu  found  that  one  hundred  parts  of  moist  soil 
absorbed  in  three  hours  only  0.4  of  ammonia,  while  the 
same  quantity  of  dry  soil  absorbed  0.28.  At  the  same 
time  2.6  per  cent,  of  water  was  absorbed  by  the  dry  soil. 

He  also  placed  0.019  parts  of  ammonia  in  juxtaposition 
with  one  hundred  parts  of  calcareous  clay  for  fi\^e  days. 
During  this  period  0.016  of  the  ammonia  had  been  ab- 
sorbed by  the  clay,  the  remainder  being  taken  up  by  the 
dew  deposited  on  the  sides  of  the  glass. 

He  also  placed  a  portion  of  moist  soil  in  a  tube  one 
foot  long,  and  caused  a  current  of  air  to  stream  through 
it,  charged  with  ammonia,  which  was  soon  all  taken  up  by 
the  soil,  which  was  found  to  contain  0.192  per  cent,  of 
ammonia.  Another  stream  of  pure  air  being  made  to 
pass  through  it,  soon  reduced  the  quantity  to  0.84  per 
cent. 

Boussingault  and  Lewy  found  ammonia  existing  in  the 
air,  in  the  interstices  of  soils  in  every  case  examined,  but 
only  in  two  instances  was  there  enough  to  determine  it  by 
weight.  In  some  cases,  it  is  proper  to  state  that  the  soil 
being  sandy,  had  been  fertilized  with  stable  manure  only 
two  days  previously,  the  air  being  taken  from  a  depth  of 
about  14  inches.  Ammonia  was  found  equal  to  thirty- 
two  parts  in  a  million.  Five  days  thereafter,  rainy  weather 
intervening,  only  thirteen  millionths  was  found. 

Ammonia,  having  a  greater  affinity  for  water,  escapes 
by  evaporation  from  the  soil  according  to  the  extent  of  the 
evaporation.  The  amount  of  ammonia  existing  in  a  soil  is 
largely  due  to  moisture.  A  clay  soil  being  a  better  ab- 
sorbent of  water  than  sand,  is  consequently  better  adapted 
to  absorb  and  retain  ammonia. 

Reiset  proved  that  a  portion  of  nitrogen  escaped  from 


AMMONIA  XOT  EFFICIENT  BY  ITSELF. 


279 


fermenting  dung  in  the  free  state.  Boussingault  found  in 
using  crushed  seeds  as  fertilizers,  that  a  portion  of  the  ni- 
trogen was  lost  in  some  gaseous  forms,  probably  both  as 
ammonia  and  free  nitrogen. 

From  these  facts  the  inference  is  clear  that  the  ammonia 
of  fertilizers,  when  applied  to  a  soil,  either  escapes  with 
other  gases  in  a  short  time,  or  is  absorbed  by  the  soil,  and 
held  till  imbibed  by  plants  or  converted  into  nitric  acid, 
and  then  combined  with  salts  forming  nitrates. 

249.  Loss  of  Ammonia  Applied  to  Crops. 

Lawes  and  Gilbert  found,  on  an  average  of  twenty  years, 
that  wheat  assimilates  about  forty-five  per  cent,  of  nitrogen 
in  a  spring  dressing  of  nitrate  of  soda;  about  thirty-three 
in  an  autumn  dressing  of  sulphate  of  ammonia;  and  only 
fourteen  and  a  half  per  cent,  of  the  nitrogen  supplied  by 
farm-yard  manure.  The  proportion  assimilated  by  barley 
of  ammonium  salts,  was  forty-nine  per  cent. 

It  was  found  upon  analysis  that  a  considerable  portion 
of  the  missing  nitrogen  was  still  present  in  the  soil,  but  in 
combinations  not  suitable  for  the  use  of  plants.  Still  more 
is  carried  ofi*by  drainage  waters,  especially  the  nitrate  of 
soda  and  ammonium  salts.  The  inference  is  that  ammonia, 
when  applied  to  the  soil,  is  soon  converted  into  nitric  acid, 
and  if  not  appropriated  at  once,  is  leached  out  by  rains. 

They  conclude  that  ammonia  should  only  be  applied  to 
crops  in  the  spring,  just  before  planting,  and  that  on  sandy 
soils  it  would  be  best  to  apply  some  organic  form  of  nitro- 
gen, as  being  more  certain  than  ammonia  or  the  nitrates. 

250.  Ammonia  not  Efficient  by  Itself, 

While  ammonia  is  a  very  important  fertilizer  with 
proper  combinations,  by  itseJf  it  will  not  increase  the  pro- 
duct of  cotton  or  the  cereals,  unless  there  is  an  abundant 
supply  of  the  seed-malving  elements  in  the  soil. 


280 


FERTILIZERS  AND  NATURAL  MANURES. 


Thus,  while  ammonia,  on  poor  land,  would  increase 
largely  the  quantity  of  hay  and  the  stalks  of  corn  and  cot- 
ton, it  would  only  add  to  the  fruit  in  proportion  to  the 
amount  of  stimulus  (to  use  a  convenient  term)  it  gives  to 
the  roots,  to  cover  a  larger  space  in  search  of  food. 

This  effect  is  observed  when  stable  manure  is  applied 
in  large  quantities  on  wheat,  w^ithout  the  seed-making  ele- 
ments: the  wheat  is  laid,  as  it  is  termed,  for  the  lack  of 
sufficiency  of  silicate  of  lime  in  the  stems,  and  the  product 
very  trifling  compared  to  the  size  of  the  straw. 

251.  Ammonia  Superior  to  the  Nitrates, 

The  most  powerful  fertilizers,  as  the  dung  of  animals, 
rotten  cotton-seed,  and  Peruvian  guano,  contain  ammonia, 
which  is  the  principal  fertilizing  element.  'No  other  nitro- 
genous compounds  act  so  well.  True,  M.  Ville  planted 
w^heat  in  calcined  sand,  and  used  ammonia  as  a  chloride 
nitrate  and  phosphate.  The  nitrate  of  potash  beat  them 
all  by  one-fourth.  Why  ?  Because  it  was  associated  with 
potash. 

One  of  the  great  virtues  of  ammonia  as  a  fertilizer  is 
the  ease  with  which  it  is  transposed  either  in  the  air,  in 
soils,  or  plants. 

None  of  the  compounds  of  nitrogen  are  so  simple  as 
ammonia,  hydrogen  being  the  element  for  which  nitrogen 
possesses  the  greatest  affinity.  It  is  extremely  soluble  in 
water,  both  as  a  gas  and  all  its  volatile  compounds.  In 
bodies  found  sixty  feet  below  the  surface  in  an  old  church- 
yard in  Paris,  all  the  nitrogen  in  the  adipocere  was  in  the 
form  of  ammonia. 

Sachs  and  Knop  found,  in  experiments  in  water  culture, 
that  salts  of  ammonia  did  not  completely  answer  as  ni- 
trates. Strohnman,  Rautenberg,  and  Kuhn  came  to  the 
same  conclusion,  using  sal  ammoniac  ;  and  Birner  and 
Lucanus,  with  the  phosphate  and  sulphate  obtained  similar 


AMMONIA  SUPEPwIOR  TO  THE  NITRATES. 


281 


results.  Kiihn  attributed  the  failure  to  the  fact  that  the 
acid  combined  with  the  ammonia  acted  as  a  poison,  when 
uncombined  in  the  plant. 

In  1861,  Hampe  made  a  fine  yield  with  a  maize  plant, 
using  a  weak  solution  of  phosphate  of  ammonia  without 
nitrates.  In  1866,  Beyer  used  carb.  ammonia  on  the  oat 
plant.  It  did  not  flourish  at  first,  but  shot  forth  toward 
the  last  with  renewed  vigor.  On  examination  the  ammo- 
nia had  been  changed  to  nitric  acid.  In  1867,  Hampe  pro- 
duced good  results  with  maize  plants,  but  at  first  they 
were  yellow  and  thriftless,  becoming  green  and  flourishing 
toward  the  last.  He  inferred  that  the  young  plants  could 
not  appropriate  ammonia  until  they  attained  a  certain  age. 
In  1868,  Wagner  repeated  these  experiments  with  similar 
results.  Beyer  reports  failure  for  three  summers  to  nourish 
the  oat  plant  with  ammonia  as  the  only  source  of  nitrogen. 

In  1870,  we  experimented  on  cotton  with  ammonia  as 
a  sulphate,  also  with  nitrates  and  nitrogen  in  an  organized 
form.  As  the  land  was  poor,  we  added  to  each  of  these 
azotized  substances,  superphosphate  of  lime  and  salt,  to 
supply  phosphoric  acid  and  chlorine.  From  rows  thirty-five 
yards  long,  we  obtained  the  following  results: 

Amount  applied :  Nit.   Soda,   2  pounds 
Sulph.  Am.,  3 
Nit.   Soda,  1 
"  "        Sulph.  Am.,  1  " 

Sulph.  Am.,  1  " 
«        Dried  flesh,  2  " 

I  This  is  conclusive  that  ammonia  acts  better  than  nitric 
acid  on  cotton.  A  combination  excels  either  separate. 
[  The  dried  flesh  was  subject  to  great  pressure,  until  all  the 
I  water  and  blood  were  pressed  out  to  prevent  decay — then 
1  ground  and  applied.  It  had  12  per  cent,  of  nitrogen.  The 
plants  grew  ofl'  vigorously — the  ammoniates  beating  the 
.    nitrates  in  rapidity  of  growth. 


.111  oz.  seed  cotton. 
.124 

132 
144 


282 


FEETILIZERS  AND  NATURAL  MANURES. 


The  present  year,  IS^S,  we  tested  the  same  substances 
in  rows  10  yards  long,  with  the  following  results: 


Product  of  Seed  Cotton. 

Amount  of  Fertilizer. 

1st 

2d 

3d 

Total. 

Picking. 

Picking. 

Picking. 

.   18  oz. 

...73  oz. 

...73  oz... 

.163  oz. 

Nitrate  of  Potassa,  533^  oz  ,  . 

23  . 

. . .74  . 

...66  ... 

.163 

.  .  46  . 

. . .97  . 

. . .54  ... 

.197 

Dried  flesh  ground,  53}^  oz .  . 

....58  . 

..115  . 

...60  ... 

.233 

14  . 

. . .68  . 

...63  ... 

.145 

Here  it  is  apparent  that  the  ammonia  is  quicker  of 
action  than  the  nitrates.  Although  there  is  less  nitrogen 
in  the  sulph.  ammonia  than  in  them.  It  is  equally  clear 
that  it  is  more  powerful  as  a  fertilizer.  This  was  exhibited 
in  the  early  growth  of  the  plants,  as  well  as  the  product. 

The  action  of  the  nitrogen  of  the  albuminoids  in  the 
dried  flesh  is  also  remarkable.  Did  it  have  to  go  through 
the  successive  stages  of  ammonia  and  nitric  acid?  We 
doubt  it.  If  so,  why  did  not  the  nitric  acid  already  pre- 
pared act  more  promptly  and  powerfully  in  Nos.  1  and  3  ? 
The  quick  and  potent  action  of  the  dried  flesh  leaves  us  to 
infer  that  some  peculiar  force  is  brought  to  bear  when  its 
decomposition  takes  place,  other  than  the  mere  nutritive 
efiect  of  the  nitrogen.  Perhaps  other  elements  are  elimi- 
nated and  rendered  soluble,  as  the  phosphoric,  sulphuric, 
and  carbonic  acids. 

252.  Ammonia  as  a  Solven^. 

Ammonia  does  not  act  simply  by  furnishing  nitrogen 
to  plants,  but  by  the  transposition  and  preparation  of  other 
materials.  Thus,  the  silicates,  felspar,  etc.,  are  decomposed 
by  it,  and  potash  made  available  ;  also  the  insoluble  phos- 
phates are  rendered  soluble  by  ammonia  in  a  soil. 

This  latter  process  is  a  very  interesting  one,  as  a  most 
powerful  compound  is  formed,  phosphate  of  ammonia; 
which  presents  at  once  the  two  most  eflicient  salts  needed 
by  plants  in  a  soluble  form. 


SOURCES  OF  PHOSPHORIC  ACID. 


283 


It  is  believed  that  the  solvent  action  of  ammonia  might 
be  rendered  so  effective  on  ground  bones,  if  reduced  to  very- 
fine  proportions,  as  to  supersede  the  action  of  sulphuric 
acid  to  a  laro-e  extent.  But  it  is  doubtful  whether  it 
would  be  a  cheaper  process. 


CHAPTER  ly. 

PHOSPHORIC  ACID.  ITS  SOURCES,  AND  RELATION  TO  PLANT 

LIFE. — ORIGIN  AND  COMPOSITION  OF  MINERAL  PHOS- 
PHATES. 

253.  Phosphoric  Acid,  P.^O^. 

Anhydrous  phosphoric  acid  never  exists  in  nature,  but 
results  in  snow-white  crystals  when  phosphorus  is  burned 
in  dry  air  or  oxygen.  It  has  no  acid  properties,  however, 
until  united  with  water,  when  it  forms  hydrated  phos- 
phoric acid,  P^O-jSH^O. 

Phosphoric  acid  is  insoluble  in  water  in  all  of  its  com- 
binations except  the  alkaline  metals,  and  in  these  are 
only  soluble  in  the  form  of  bi-phosphate.  This  salt  is 
produced  by  the  action  of  sulphuric  and  hydrochloric 
acids  on  the  neutral  phosphate. 

Under  the  form  of  hydrated  phosphoric  acid  it  unites 
with  various  bases,  forming  phosphates,  wiiich  constitute 
the  most  important  ingredients  of  plants. 

254.  Sources  of  Phosphoric  Acid. 

The  sources  of  phosphoric  acid  are  raw  bone,  bone 
ash,  boneblack,  rock  guanos,  coprolites,  marl  stones,  apa- 
tite, and  phosphorite. 

The  demand  for  raw  bone  in  the  arts,  precludes  it  to  a 
large  extent  from  superphosphate  manufacturers.  Pone 
ash  is  used  more  extensively  in  this  country  for  this  pur- 
pose, being  mixed  with  the  ground  phosphates,  adding  to 


284 


FERTILIZERS  AND  NATURAL  MxiXURES. 


their  solubility.  It  is  mostly  brought  from  the  La  Platte 
District,  South  America.  It  is  prepared  from  bones  of 
slaughtered  cattle  by  burning  in  the  open  air,  by  which 
the  carbon  and  orga^nic  matter  escape. 

Boneblack^  or  animal  charcoal,  is  made  by  driving  off 
all  the  volatile  matters  by  calcination,  except  the  carbon. 
It  is  ground  and  sold  to  the  sugar-refiners  for  bleaching 
their  solutions.  After  being  used  several  times  in  this 
way,  it  is  bought  to  make  superphosphates,  as  it  retains 
most  of  the  phosphate  of  lime  besides  "organic  matters, 
acquired  especially  when  used  with  blood.  The  phos- 
phate of  lime  in  this  and  in  bone  ash  is  slightly  assimi- 
lable by  growing  crops,  one  part  being  soluble  in  6,800 
parts  of  carbonic  acid  water.  In  the  presence  of  alkaline 
salts,  this  solubility  is  increased. 

Apatite  is  found  in  veins  of  volcanic  and  crystalline 
rocks  both  in  Europe  and  America.  The  Norway  variety 
differs  from  all  others  in  being  free  from  fluoride  of  cal- 
(dum.  The  Canadian  has  a  high  percentage  of  sulphate 
of  lime,  but  a  cemented  structure,  rendering  it  unfit  for 
direct  application.  This  mineral  is  difficult  to  obtain, 
though  abundant. 

The  best  specimens  oi pJiospJwrite  are  from  Spain  and 
Bavaria.  It  becomes  phosphorescent  when  heated.  There 
is  also  a  fine  bed  of  this  mineral  in  Wales. 

The  principal  phosphotic  guanos  in  use  in  Europe,  are 
the  Cambridge  coprolites.  Sombrero  phosphate,  Spanish 
phosphate  from  Estremadura,  and  German  phosphate.  In 
this  country  the  principal  ones  are  theNevassa  and  Ashley 
phosphates — the  latter  found  on  the  coast  of  South  Caro- 
lina. 

Coprolites,  as  those  of  Cambridge,  are  supposed  to 
be  the  excrements  of  Saurian  and  other  antediluvian  ani- 
mals. The  Ashley  phosphates  abound  in  fossil  vertebrae 
and  sharks'  teeth,  showing  their  origin,  while  Nevassa, 


EELATIOX  OF  PnOSPHOKIC  ACID  TO  PLAXTS. 


2S5 


occurring  in  large  quantities,  with  a  porous  texture,  are  of 
more  doubtful  origin,  though  believed  to  be  fossil iferous. 

255.  Ilelation  of  Fhosphoric  Acid  to  Plants, 

Phosphoric  acid  seems  to  be  an  exception  to  the  general 
rule  governing  other  substances,  in  that  it  occtirs  in  ZSTature 
almost  exchisively  in  forms  not  assimilable  by  plants,  and 
even  when  taken  up  by  them  and  converted  into  organized 
bodies,  whether  animal  or  vegetable,  the  same  insoluble 
forms  are  assumed.  Thus  the  bones  of  all  animals,  and 
the  seeds  of  all  plants  have,  in  .  large  proportions,  phos- 
phoric acid  combined  as  the  insoltible  tri-basic  or  bone 
phosphate  of  lime,  which,  in  that  form,  would  remain  un- 
appropriated by  plants,  unless  changed  by  slow  chemical 
action  in  the  soil. 

The  common  forms  in  wliich  potash,  soda,  magnesia, 
sulphuric  acid,  and  chlorine  exist  in  soils,  are  more  or  less 
soluble.  Lime  is  less  so  than  the  others,  but  this  is  com- 
pensated by  its  abundance.  Carbonate  and  sulphate  of 
lime  are  both  only  slightly  soltible ;  but  there  is  generally 
enough  in  most  soils  to  supply  any  crop.  The  above  sub- 
stances having  become  soluble,  generally  remain  so. 

TThen  phosphoric  acid  is  rendered  soluble,  by  being 
changed  from  a  neutral  to  a  bi-phosphate,  it  is  liable  at  anv 
time  to  be  again  reduced  unless  appropriated  very  soon  l;y 
growing  jilants.  Thus,  by  a  wise  provision  of  Providence, 
that  substance  in  nature  the  sparsest,  and  the  most  often 
required  as  plant-food,  is  locked  up  in  insoluble  combina- 
tions, to  save  it  from  a  waste  which  would  constantly 
transpire,  if  like  other  substances,  it  remained  in  a  soluble 
condition  in  the  soiL 

If  the  unadtilterated  bone  phosphate  of  lime  (3C0,P0,), 
the  common  form  in  which  lime  and  phosphoric  acid 
imite  in  nature,  be  applied  as  a  fertilizer  (say  to  cotton), 
in  a  soil  with  but  little  organic  matter,  it  would  produce  but 


286 


FERTILIZERS  AND  NATURAL  MANURES. 


little  more  than  the  soil  without  it.  If,  however,  ammonia 
in  some  form  be  combined  with  it,  or  chloride  of  sodium 
(common  salt),  there  would  be  a  very  sensible  increase  of 
production,  not  so  much  from  the  intrinsic  virtue  of  the 
ammonia  and  the  salt,  as  the  fact  that  these  substances 
render  the  insoluble  phosphate  of  lime  soluble,  by  changing 
its  form. 

The  same  effect  would  be  produced  in  a  soil  abound- 
ing in  organic  matter,  by  the  carbonic  acid  produced  in 
it.  Phosphoric  acid  is  not  only  important  in  supplying 
plants  with  food,  but  acquires  a  double  importance  in  the 
fact  that  it  aids,  through  green  crops,  in  bringing  nitrogen 
from  the  atmosphere  to  form  ammonia,  which  in  its  turn  un- 
locks the  natural  stores  of  potash,  and  other  undeveloped 
minerals  of  the  soil,  and  thus  renders  them  available.  It 
is  thus  a  source  of  nitrogen  directly,  and  potash  indirectly. 

256.    Origin  of  Mineral  Phosphates, 

The  probable  origin  of  the  various  deposits  of  mineral 
phosphates,  has  attracted  much  attention  among  chemists 
and  agriculturists.  Several  theories  have  been  advanced ; 
but  no  very  satisfactory  conclusions  have  been  reached  in 
most  cases. 

Even  the  old  and  well-established  theory  as  to  the  ori- 
gin of  the  ammoniated  phosphates  of  the  Peruvian  islands 
being  the  deposit  of  sea  fowls,  has  been  recently  called  in 
question,  and  another,  but  much  less  likely  theory,  an- 
nounced. 

Some  phosphate  rocks,  as  sombrerite,  it  is  believed,  have 
been  produced  from  the  action  of  water  on  deposits  of 
birds,  and  the  subjacent  calcareous  rocks.  Phosphoric 
acid  being  eliminated  in  the  water,  uniting  with  the  lime 
as  a  base,  and  thus  forming  phosphate  of  lime.  Many  de- 
posits could  not  have  been  formed  in  this  way,  however. 

Profs.  Dyer  and  Kerr  suggest  that  the  brachiopods 


COMPOSITION  OF  PHOSPHATES. 


287 


may  have  supplied  a  large  percentage  of  these  deposits. 
It  is  known  that  the  recent  Lingitla  has  over  eighty 
per  cent,  of  phosphate  of  lime  in  the  mineral  ingredients 
of  its  shell.  Prof.  Dyer  thinks  that  large  quantities  of 
phosphate  of  lime  in  the  Laurentian  and  Silurian,  as  well 
as  the  Devonian  and  carboniferous  strata,  are  derived 
from  this  source. 

In  the  mesozoic  and  tertiary  strata,  in  South  Carolina, 
the  phosphates  occur  in  the  form  of  nodules,  instead  of 
veins  or  beds.  The  hypothesis  of  Mr.  Lankester,  that  these 
nodules  were  formed  by  the  union  of  clay  and  phosphate 
of  lime,  based  upon  the  property  possessed  by  clay  of 
detaching  phosphate  of  lime  from  its  solution  in  carbo- 
nated water,  is  very  reasonable;  as  the  nodules  in  question 
seem  to  be  bits  of  clay,  which  have  been  imbedded  with 
great  quantities  of  bones  and  sea-weed,  which  aided  in  the 
formation  of  the  carbonic  acid,  which  dissolved  the  phos- 
phate. These  nodules  are  always  formed  in  connection 
with  argillaceous  strata. 

But  if  it  be  true,  as  is  believed,  that  these  phosphate 
beds  are  mostly  of  organic  origin,  how  does  it  happen 
that  so  many  animals  were  congregated  in  one  place,  as 
the  shells,  bones,  and  excrements  clearly  show.  Some 
have  accounted  for  it  on  the  principle  of  whirlpools, 
which  have  brought  many  floating  dead  bodies  for  many 
miles  of  circumference  into  its  vortex  ;  others,  with  more 
show  of  reason,  infer  that  these  places  were  favorite  resorts 
of  certain  shell-fish,  as  the  brachiopods,  where  they  would 
breed  and  die  in  immense  quantities :  the  shells  of  other 
fish,  and  bones  of  vertebrates,  being  incidentally  deposited 
at  a  much  later  period. 

257.    Composition  of  Mineral^  and  other  Phosphates, 
The  bone  phosphate  of  lime  prevails  in  most  minerals, 
but  in  some  cases,  the  phosphate  of  alumina.    They  have 


288 


FERTILIZERS  AND  NATURAL  MANURES. 


a  close,  compact  structure,  not  so  easily  acted  upon  as  bone 
ash,  and  require  a  stronger  acid  or  more  of  it.  Phosphates 
which  have  much  silicious  matter,  carbonate  of  lime  or 
oxide  of  iron,  are  objectionable.  Particularly  the  last  two, 
as  the  iron  will  reduce  the  superphosphate  when  made,  to 
an  insoluble  phosphate  of  iron,  according  to  the  percentage 
in  it,  if  not  used  immediately.  The  carbonate  of  lime  re- 
quires a  portion  of  the  sulphuric  acid  to  neutralize  it,  before 
it  reaches  the  phosphate  of  lime.  This  much  is  lost. 
Hence,  phosphates  of  this  kind  are  avoided. 

The  following  table  from  Morfit  shows  the  relative 
amount  of  bone  phosphate  of  lime  in  the  substances  named  : 

Bone  Cam-  Marl 

Ash,  Bone     Sombrero   bridge  Stones,  Nava- 

South  Black.     guano.      copro-      South  sa, 

American.  lites.  Carolina. 

Bone  Phos.  Lime.  .70.31. .  .58.10. .  .67.06. .  .57.09. .  .52.21. .  .46.80 

Carb.  Lime  10.82...  8.80...  5.24. ..  13.27.  .*14. 32. . .  1.92 

Oxide  of  Iron  60   1.10.. .  trace  . .  .trace  . . .  3.70 

Sand  and  Silica....  9.20...  4.00...    .68...  6.93. . .13.96. . .  4.50 

Prof.  Morfit  values  the  South  Carolina  phosphates 
above  all  others,  in  their  abundant  and  regular  supply, 
the  comparative  small  percentage  of  iron  and  carbonate 
of  lime,  and  the  ease  with  which  they  may  be  ground. 
Although. the  average  of  phosphate  of  lime  is  only  me- 
dium, yet  their  accessibility  and  cheapness  render  them 
more  available  than  any  others.  They  exist  principally 
on  the  Ashley  River,  and  the  fish  beds  from  whence 
they  are  taken  range  from  forty  to  fifty  miles  in  extent. 
Specimens  from  near  Williman's  Island,  analyzed  by  Dr. 
Voelcker,  have  traces  of  nitrogenous  organic  matter,  indi- 
cating their  origin. 

The  Navasa  guano  is  from  an  island  of  that  name  near 

*  This  refers  to  lime  with  organic  acids,  silica,  and  alumina, 
which  makes  the  carbonate  much  less. 


MANUFACTUKE  OF  SUPEKPHOSPHATES. 


2S9 


Hayti,  W.  1.  Next  to  the  South  Carolina,  it  is  more  ex- 
tensively used  in  this  country  than  any  other.  It  contains 
unusual  quantities  of  iron  and  alumina,  which  is  a  disad- 
vantage. 


CHAPTEE  V. 

SUPERPHOSPHATES. — THEIR  MANUFACTURE    AND  COMPOSI- 

XIOX.  PRECIPITATED,     REDUCED,     AND  AMMONIATED 

PHOSPHATES. 

25S.  Manufacture  of  Superphosphates, 

Put  a  small  piece  of  bone  in  a  wine  glass,  and  pour 
dilute  sulphuric  acid  upon  it.  It  will  be  dissolved  in  a 
short  time,  and  the  white  precipitate  is  known  in  commerce 
as  superphosphate. 

Bones  vary  in  their  amount  of  phosphate,  according  to 
the  kind  of  animal,  its  age  and  food.  An  average  would 
be  about  55  per  cent.  Then  100  lbs.  of  bones  would  have 
55  of  phosphate  of  lime,  and  about  3  of  carbonate  of  lime. 
The  first  3  lbs.  of  sulphuric  acid  would  be  wasted  to  reduce 
the  carbonate  to  a  sulphate  of  lime. 

The  phosphoric  acid  in  bone  exists  as  a  tri-calcic  or 
tri-basic  phosphate  of  lime.  The  sulphuric  acid  takes 
away  two  equivalents  of  lime,  and  with  two  double 
equivalents  of  water,  forms  hyd rated  sulphate  of  lime 
(known  in  commerce  as  gypsum,  or  land  plaster),  leaving 
the  phosphoric  acid  with  one  equivalent  of  lime,  and  two 
of  water  as  bi-phosphate. 

In  making  superphosphates  there  is  so  much  heat  pro- 
duced, as  to  dispel  a  large  quantity  of  water,  which  must 
be  added  to  keep  up  the  proper  solubility.  For  if  heated 
too  long,  the  tri-phosphate  will  lose  a  portion  of  its  solu- 
bility. High  heat,  amounting  to  fusion,  will  render  it 
wholly  insoluble. 

13 


290 


FERTILIZERS  AND  NATURAL  MANURES. 


It  requires  machinery  of  great  power  to  grind  down 
minerals  and  marl  stones  to  what  is  termed  ho7ie  dust  for 
the  manufacture  of  superphosphates.  This  term  in  Europe 
is  confined  to  phosphates  prepared  from  rock  and  fossil 
guanos ;  and  those  made  of  bone  ash,  raw  bone,  etc.,  are 
termed  dissolved  hones.  In  this  country,  however,  the 
terms  are  interchangeable.  We  have  superphosphates 
made  of  Ashley  or  Navasa  exclusively;  and  then  combined 
with  bone  ash,  boneblack,  and  raw  bone,  under  the  general 
term  of  superphosphates,  or  dissolved  bones. 

Within  a  few  years,  great  improvements  have  been 
made  in  the  manufacture  of  superphosphates,  by  which  a 
much  higher  amount  of  solubility  is  obtained,  much  more 
uniformity  secured,  and  much  less  water  and  insoluble  sub- 
stances allowed  to  remain.  Bone  dust  is  used  in  conjunc- 
tion with  mineral  phosphates,  while  a  high-graded  article 
can  be  furnished  cheaper,  made  in  less  time,  and  in  better 
mechanical  division  than  formerly.  The  first  mineral 
phosphate  ever  used  in  this  way,  was  apatite  from  Norway. 
This  has  been  abandoned,  as  better  deposits  have  been  found. 

One  reason  why  superphosphates  act  so  well,  is  the 
complete  breaking  up  of  the  mass  into  such  a  fine  powder 
as  to  have  every  part  of  it  exposed  to  the  action  of  natural 
solvents  in  the  soil.  There  can  be  no  question,  however^  that 
their  main  virtue  lies  in  their  great  solubility.  In  the  South, 
especially,  where  lands  are  cheap,  and,  under  a  wretched 
system  of  culture,  have  been  exhausted  of  nitrogen  and 
phosphoric  acid,  it  is  requisite  to  have  concentrated  quick- 
acting  fertilizers,  to  manure  the  crops  rather  than  the  land. 
Such  are  superphosphates — the  more  soluble  the  better, 
because  the  quicker. 

259.  Hydrous  Sulphuric  Acid^  SO3HO. 

The  hydrous  sulphuric  acid,  oil  of  vitriol,  has  81.63  per 
cent,  of  dry  or  anhydrous  acid,  and  18.37  of  water.  This 
is  not  only  the  strongest  of  all  the  acids,  but  the  range  and 


HYDROUS  SULPHURIC  ACID. 


291 


strength  of  its  affinities  make  it  the  most  useful  chemical 
agent  known  to  science.  It  now  plays  a  very  important 
part  in  agriculture,  many  factories  being  erected,  and  mil- 
lions of  dollars  invested  for  no  other  purpose  than  the 
manufacture  of  superphosphates.  It  is  both  cheap  and 
abundant,  as  Avell  as  powerful,  decomposing  nearly  all  the 
salts  of  other  acids. 

Sulphuric  acid  is  made  by  throwing  into  large  leaden 
chambers,  quantities  of  sulphur,  with  a  little  nitric  acid, 
and  water  as  steam,  which,  with  the  atmospheric  air,  act 
and  react  upon  each  other,  producing  large  quantities  of 
this  acid.' 

There  are  two  grades  of  sulphuric  acid  in  commerce : 
the  oil  of  vitriol,  sp.  gr.  1.846,  and  the  brown  chamber  acid, 
l.VOO.  The  last  is  as  it  came  from  the  chamber,  and  the 
first  having  been  concentrated  in  glass  or  platinum  vessels, 
becomes  the  monohydrated  sulphuric  acid.  There  are 
weaker  acids  used  in  the  factories,  running  down  in  sp.  gr. 
as  low  as  1.250. 

The  oil  of  vitriol,  when  pure,  is  transparent  and  color- 
less, of  oily  consistence,  freezes  at  29°  below  zero,  and  boils 
at  260^  F.  It  unites  so  rapidly  with  water,  that  great 
care  is  necessary  in  mixing  them,  because  of  the  heat  gen- 
erated. 

The  tw^o  acids  of  commerce  are  merely  solutions  of  the 
anhydrous  acid  of  different  strengths.  The  oil  of  vitriol  is 
much  more  economical  for  manufacturing  purposes.  It  is 
put  up  in  heavy  glass  carboys,  thirteen  to  the  ton.  As  it  is 
very  combustible,  public  carriers  charge  high  for  its  trans- 
portation; hence  it  is  important  to  have  superphosphatie 
factories  near  by,  or  at  the  place  of  its  manufacture. 

It  takes  64  lbs.  of  oil  of  vitriol  to  convert  100  lbs.  of 
bone  phosphate  of  lime  into  soluble  bi-phosphate,  while  it 
requires  82  pounds  of  the  bi-phosphate  to  effect  the  same 
end.  For  every  pound  of  carbonate  of  lime  in  bones  or 
rock  guano,  there  would  be  0.98,  pounds  of  the  strong  acid 


292 


FERTILIZERS  AND  NATURAL  MANURES. 


wasted,  and  1.26  of  the  brown.  It  requires  no  little  skill 
and  practice  to  manufacture  crude  rock  guanos  into  soluble 
food  for  plants. 

260.    Composition  of  Superphosphates, 

One  hundred  and  thirty-four  lbs.  of  dilute  sulphuric 
acid  added  to  156  lbs.  of  lime,  making  290  lbs.,  will  be 
transposed  into  118  lbs.  of  bi-phosphate,  and  172  of  sul- 
phate of  lime.  So  that  a  pure  superphosphate  would  stand 
thus:  bi-phosphate  of  lime  40.69  jDer  cent.,  sulphate  of 
lime  59.31. 

Thus  it  is  seen  that  six-tenths  of  a  superphosphate  is 
land  plaster ;  and  yet  we  have  formulas  for  concentrated 
fertilizers  which  have  this  salt  added  in  considerable  quan- 
tities to  an  already  overcharged  compound.  The  value 
of  superphosphate  would  be  much  reduced  if  we  could 
cheaply  abstract  the  better  part  of  the  plaster  instead  of 
adding  to  it. 

But  there  are  no  pure  superphosphates;  hence  the  actual 
percentage  of  bi-phosphate  of  lime  is  much  lessened.  Com- 
mercial superphosphates  will  average  from  twenty  to 
twenty-five  per  cent,  of  soluble  phosphate,  the  remainder 
being  plaster,  sand,  clay,  or  iron,  according  to  the  per- 
centage in  the  original  mineral  phosphates. 

A  pure  superphosphate  is  now  manufactured  in  England 
under  a  patent  which  claims  to  have  80  per  cent,  of 
soluble  phosphate.  This  is  certainly  a  step  forward,  as  the 
cost  of  freight  will  be  much  reduced. 

261.  Bi-Phosphate  of  Lhne,  Ca02HO,P05. 

The  bi-j)hosphate  of  lime  occurs  in  nature,  but  very 
sparsely  in  certain  waters  and  organic  matters.  It  is  pre. 
pared  artificially  by  the  action  of  dilute  sulphuric  acid  on 
the  bone  phosphate  of  lime,  called  also  tri-calcic  phos- 
phate of  lime,  and  neutral  phosphate  of  lime.    This  latter 


HOME-MADE  SUPERPHOSPHATE. 


293 


term,  however,  is  also  applied  to  cli-phosphate  of  lime 
(2Ca02HO,PO,). 

As  before  stated,  this  phosphate  being  soluble,  is  the 
form  through  which  plants  receive  their  phosphoric  acid; 
the  evidence  of  which  is  found  in  the  fact,  that  they  always 
thrive  under  its  action  when  applied  to  the  soil,  and  never 
under  the  action  of  any  other  phosphate,  unless  connected 
with  solvents  which  are  capable  of  changing  their  forms. 

Bi-phosphate  of  lime  is  the  ingredient  from  which  com- 
mercial superphosphates  receive  all  their  value.  It  gene- 
rally constitutes  from  twenty  to  twenty-five  per  cent,  of 
this  class  of  fertilizers. 

262.  Home-made  Superphosphate, 

Superphosphates  may  be  manufactured  at  home,  by 
gathering  up  a  sufficient  quantity  of  dry  bones,  making  a 
large  heap  mixed  with  dry  pine  wood,  and  burning  the 
whole  mass  to  ashes.  Pound  and  sift  until  the  ash  is 
reduced  to  a  powdered  mass.  Now  have  ready  a  box, 
water-tight,  of  suitable  dimensions,  into  which  put  the 
bone  ash,  and  add  sufficient  water  to  wet  the  mass  thor- 
oughly. Then  take  the  brown  acid  of  commerce,  and  to 
every  gallon  add  about  four  gallons  of  water.  Pour  on 
the  moistened  bone  ash  this  diluted  acid,  slowly,  keeping 
several  hands  stirring  with  wooden  paddles.  Great  care 
must  be  taken  in  pouring  the  acid  from  tlie  carboys  lest  a 
droplet  spirts  in  the  eye,  w^hich  might  put  it  out.  Old 
clothes  and  aprons  sliould  also  be  used,  as  it  is  impossible 
to  protect  the  clothing  from  a  sprinkling  of  acid.  Con- 
tinue to  j)our  on  the  acid  until  the  contents  of  the  box  be- 
comes a  semi-fluid  mass,  and  all  effervescence  ceases. 

As  a  general  rule,  one  carboy  of  acid  might  be  used  on 
300  lbs.  of  bone  ash.  Some  of  the  finest  of  the  ashes  sifted 
through  a  fine  sieve  should  be  reserved  and  added  toward 
the  last,  as  the  first  step  in  the  drying  process.    This  will 


294 


FERTILIZERS  AND  NATURAL  MANURES. 


serve  to  take  up  any  of  the  acid  which  might  not  be  appro- 
priated. The  stirring  should  be  continued  at  intervals  for 
eight  or  ten  hours,  or  even  longer,  if  the  chemical  action 
seems  not  to  be  completed.  When  the  mass  begins  to  dry 
and  becomes  cemented,  the  drying  material  should  be  used 
at  once,  and  the  stirring  resumed,  until  the  whole  assumes 
a  friable,  pulverulent  character. 

The  drying  material  may  be  prepared  from  well-rotted 
chip  manure,  thoroughly  sifted  and  air-dried,  or  sawdust, 
or  the  scrapings  of  the  horse  pound,  or  the  dry  earth  from 
under  an  old  house,  or,  if  nothing  better,  fine  sand.  When 
thoroughly  sifted  and  dried,  add  in  sufficient  quantities  to 
effect  the  desired  purpose. 

Three  carboys  of  acid  (450  lbs.)  to  900  lbs.  of  bone  ash, 
with  say  650  lbs.  of  drying  material,  will  prepare  a  ton  of 
superphosphate  at  a  cost  of  about  $30  (to  say  nothing  of 
the  labor)  about  equal  to  most  that  you  will  find  on  sale  in 
the  markets:  these  vary  from  10  to  33  per  cent,  of  soluble 
bone  phosphate  of  lime.  Seven  hundred  and  fifty  lbs.  of 
this  home-made  superphosphate  made  into  a  compost  with 
1,250  lbs.  of  cotton  seed,  or  dry  stable  manure,  will  fur- 
nish a  ton  of  good  ammoniated  superphosphate,  for  about 
$12  paid  out  for  acid  and  bones. 

By  husbanding  all  the  material  of  the  farm,  and  buying 
bones  in  the  neighborhood,  a  painstaking  small  farmer 
might  make  nearly  enough  for  his  own  use  without  pur- 
chasing commercial  fertilizers.  As  labor  is  money,  it  is 
proper  to  add  it  to  the  cost ;  and  it  takes  no  little  labor, 
care,  and  skill,  to  husband  materials,  make  manure,  and 
haul  out  and  apply.  The  great  advantage  in  concentrated 
fertilizers  prepared  by  machinery,  is  in  their  being  so 
portable  and  easy  of  application.  Nevertheless,  all  farmers 
should  make  as  much  as  they  could  conveniently  for  their 
near  fields,  purchasing  what  is  most  needed  for  the  more 
distant. 


LIQUID  BI-PHOSPHATE  OF  LIME. 


295 


263.  Effect  of  Liquid  Bi-phosphate  of  Lime  as  a  Fertilizer, 

In  order  to  test  the  action  of  a  pure  solution  of  bi-phos- 
phate of  lime  applied  in  a  liquid  form  against  its  residue, 
and  the  dry  superphosphate,  we  took  13^  oz.  of  super- 
phosphate, which  had  33  per  cent,  of  dissolved  bone  phos- 
phate of  lime,  and  filtered  out  of  it  all  that  would  dissolve 
in  cold  water.  The  residue  was  dried  and  weighed,  being 
8  oz.  The  following  table  exhibits  the  result  in  rows  of 
cotton  17^  yards  long  on  a  poor,  gravelly  soil. 

Table  showing  the  efiect  of  liquid  bi-phosphate  of  lime 
as  a  fertilizer  against  its  residue ;  and  the  dry  super- 
phosphate (at  Athens,  Georgia,  1873). 

1st         2d       3d  J,  _ 

Pick-  Pick-  Pick-  Total.  ^cre 
ing.        ing.     ing.  at-re. 

Bi-phosphate  as  a  liquid,  5}^  oz. .  .19  oz.  .41  oz.  .3  oz.  .63  oz.  .945 

Residue,  8  oz  12     ..29     ..2     ..43  ..645 

Superphosphate,  dry,  8  oz  19     . .  25     . .  2     . .  46     . .  690 

"    133^  oz  27     ..29     ..2     ..58  ..870 

No  manure   7     ..52     ..3     ..32  ..480 

This  indicates  that  the  liquid  form  is  the  best  to  apply 
soluble  fertilizers,  as  is  clearly  seen  in  contrasting  the 
residue  with  the  others  which  had  equal  quantities  soluble 
in  water,  the  dry  superphosphate  having  the  advantage 
of  the  residue  besides,  in  which  was  a  portion  readily 
soluble  in  carbonic  acid  in  the  soil.  This  is  evidenced  by 
comparing  the  residue  (none  of  which  was  soluble  in  cold 
water,)  with  the  natural  soil.  It  is  remarkable  also,  that 
the  8  oz.  of  residue  made  nearly  as  much  as  the  9  oz.  of 
superphosphate.  This  is  owing,  doubtless,  to  the  fact  that 
where  a  small  quantity  of  bi-phosphate  only  comes  in 
contact  with  the  soil,  it  is  more  liable  to  meet  with  bases 
and  become  insoluble. 

The  superior  effect  of  the  liquid  over  the  dry  superphos- 
phate, is  doubtless  owing  to  its  extreme  diffusibility  in  that 


296 


FERTILIZERS  AND  NATURAL  MANURES. 


form,  by  which  it  spreads  over  a  much  larger  surface  of 
soil,  and  keeps  up  a  more  uniform  supply  during  the  season. 
Thus,  while  the  first  picking  fell  behind  the  dry  superphos- 
phate, the  last  was  considerably  in  advance  of  it. 

264.  Precijntated  Phospliate  of  Lime, 

The  precipitated  phosphate  of  lime  seems  to  be  of  the 
same  composition  as  the  bone  phosphate,  only  w^ith  the 
addition  of  from  four  to  six  equivalents  of  water.  The 
symbol  would  be  3CaO,P05+4HO  or  +6H0,  according 
to  its  mode  of  drying,  etc.  It  is  prepared  from  a  solu- 
tion of  di-  or  tri-phosphate  of  lime  in  acids,  being  precipi- 
tated with  alkalies  or  alkaline  earths. 

Morfit  is  of  opinion  that  this  precipitate  comprises 
the  several  kinds  of  phosphates,  varying  according  to  tem- 
perature and  dilution,  and  the  quality  of  the  precipitant 
used.  In  its  fresh  pulpy  state,  it  is  very  soluble  in  acetic 
and  weak  acids,  and  divides  into  soluble  forms  under  solu- 
tions of  carbonic  acid,  and  ammonia,  and  common  salt. 
It  is  probable  that  it  is  gradually  converted  in  the  soil  by 
carbonic  acid  into  di-phosphate,  and  bi-phosphate  and 
carbonate  of  lime.  When  precipitated  by  whiting,  Morfit 
calls  it  the  Columbian  phosphate  of  lime ;  when  by  am- 
monia, the  precipitated  phosphate. 

Prof.  Morfit  believes  this  phosphate  will  prove  quite  as 
potential  as  the  bi-phosphate,  under  the  action  of  natural 
solvents,  in  the  soil.  It  is  prepared  by  precipitation  from 
acid  solutions  of  animal  or  mineral  bone  phosphate,  at  much 
less  cost  as  he  supposes.  He  thinks  that  a  change  takes 
place  in  the  soil,  the  bi-phosphate  going  back  into  a  tri-  or 
di-phosphate,  before  it  has  had  time  to  exert  much  action, 
because  of  its  direct  solubility.  And  that  through  the 
influence  of  carbonic  acid  and  saline  and  ammoniated 
associates,  the  growling  crops  assimilate  it  in  that  form. 

We  do  not  share  with  him  in  the  opinion  that  it  can  b^ 


REDUCED  PIIOSPIIATEf.. 


207 


made  as  efilcient  as  the  bi-phosphate  as  a  fertilizer,  nor  do 
we  see  how  it  can  be  manufactured  any  cheaper  by  the  quan- 
tity. Nor  are  we  prepared  to  concede  that  the  bi-phosphate 
is  reduced  to  that  state  in  the  soil,  and  afterward  made 
available  by  the  action  of  carbonic  acid  and  other  sub- 
^   stances.    On  the  contrary  we  are  well  convinced  that  the 
j  preeminence  of  the  bi-phosphate  over  all  other  forms,  lies  in 
:  the  fact  that  it  is  soluble  in  water,  without  the  intervention 
of  carbonic  acid,  or  anything  else,  so  that  every  rain  that 
falls  prepares  an  amount  of  soluble  phosphoric  acid  for  the 
;   plants  to  feed  upon. 

265.  lleduced  Phosphates, 

In  commercial  superphosphates,  there  is  more  or  less 
carbonate  of  lime,  oxide  of  iron,  alumina  and  undecom- 
posed  ground  phosphate  in  the  tri-basic  form,  which  have 
the  effect  to  make  the  soluble  bi-phosphate  go  back  to  a 
di-  or  tri-phosphate  of  lime,  or  an  insoluble  phosphate  of 
iron  and  alumina,  even  in  the  bags. 

There  is  much  difference  of  opinion  as  to  the  real  agri- 
cultural value  of  this  reduced  phosphate.  Some  chemists 
believe  that  it  has  about  the  same  virtue  as  the  bi-phos- 
phate, and  some  experiments  look  that  w^ay. 

They  contend  that  when  an  acid  phosphate  is  put  into 
a  moist  soil,  it  is  thrown  back  within  24  hours,  and  that 
the  reversion  does  not  injure  when  produced  beforehand. 
Some  chemists,  admitting  this  position  as  true,  never- 
theless contend  that  even  here  the  acid  phosphate  has  a 
better  opportunity  of  diffusion,  being  more  completely 
mixed  with  the  soil,  and  thus  presents  a  greater  surface  to 
the  fibrils  of  plants. 

We  admit  there  is  a  going  back  of  the  soluble  bi-phos- 
phate to  the  di-  or  tri-phosphate  under  certain  circum- 
stances, both  in  the  soil  and  in  bulk.  But  this  process  is 
not  very  rapid,  as  has  been  tested  in  old  superphosphates. 
13* 


FERTILIZERS  AND  NATURAL  MANURES. 


In  a  soil  abounding  in  lime,  it  may  be  so  rapid  as  to  deprive 
the  crop  to  a  large  extent  of  its  immediate  benefit.  Alu- 
mina, iron,  and  other  bases  will  act  in  the  same  way,  per- 
haps not  to  the  same  extent. 

We  are  not  prepared  to  admit,  however,  that  the  bi 
phosphate  is  all  so  readily  thrown  back,  much  less  within 
so  short  a  space  of  time  ;  or  that  the  reverted  phosphate 
has  anything  like  the  agricultural  value  of  the  soluble 
phosphate.  This  will  appear  evident  when  we  remember 
that  most  of  the  worn  soils  of  the  South  have  l)ut  a  small 
j)ercentage  of  organic  matter,  and  that  a  reduced  phos- 
phate could  have  but  little  effect  in  a  soil  deprived  of 
organic  matter,  because  the  principal  source  of  its  solvents, 
carbonic  acid,  ammonia,  humic  acid,  and  the  organic  acids, 
would  all.  be  comparatively  absent  from  such  a  soil. 

An  experiment  made  by  Prof.  Leroy  Broun,  1872, 
proved  very  clearly  that  a  portion  of  soluble  bi-phosphate 
was  reduced  to  an  insoluble  form  in  clay  and  sand.  He 
took  a  lump  of  clay  weighing  one  pound,  placed  it  in  a 
bottle  having  a  hole  in  the  bottom ;  and  poured  upon  it 
water  containing  soluble  phosphoric  acid.  It  was  found 
that  scarcely  a  trace  of  the  acid  (and  then  not  until  con- 
siderable quantities  were  used),  came  through  the  clay 
with  the  water.  It  had  been  absorbed  and  held  in  some 
insoluble  form. 

It  is  easy  to  perceive  how  a  grain  of  phosphoric  acid, 
made  to  permeate  by  its  extreme  diffusibility  every  parti- 
cle of  a  lump  of  5,760  grains  of  clay,  containing  so  many 
bases  with  strong  affinities  for  this  acid,  would  unite  with 
enough  to  reduce  so  small  an  amount.  This  accounts  for 
the  fact  that  soluble  phosphates  never  produce  remarkable 
results  broadcast. 

This  was  satisfactorily  tested  by  us  in  1871,  when  it  was 
found  that  100  lbs.  in  the  drill  produced  better  results  than 
five  hundred  pounds  broadcast.    The  latter  found  plenty 


EEDUCED  AND  UNEEDUCED  PHOSPHATE. 


299 


of  bases  in  the  whole  soil  to  reduce  the  solubility  before 
the  rootlets  found  it,  while  the  former  had  enough  remain- 
ing doubtless,  in  direct  contact  with  the  roots,  to  give  the 
plants  a  vigorous  start. 

266.  Experiments  with  Reduced  and  Unreduced 
Phosphate, 

With  reference  to  the  effect  of  the  reduction  of  the  bi- 
phosphate  to  the  tri-calcic  phosphate,  there  can  be  no  ques- 
tion. Liebig,  long  since,  announced  that  such  would  be 
the  effect  in  applying  superphosphates  to  lime  soils,  which 
has,  however,  been  denied  by  other  chemists.  Even  Gilbert 
and  Lawes  have  advocated  such  a  combination.' 

With  a  view  of  ascertaining  the  effect  produced  on  a 
superphosphate  reduced  by  the  action  of  caustic  lime  to  a 
tri-basic  phosphate  ;  equal  quantities  of  lime  (partially  air 
slaked)  and  superphosphate  were  mixed  dry,  and  water 
added  so  as  to  make  into  a  thick  paste,  which  was  dried 
and  pulverized,  and  then  applied  in  rows  70  yards  long, 
planted  in  cotton  ;  the  soil  being  in  good  heart,  as  is  seen 
from  the  number  of  pounds  produced  per  acre  without 
manure. 

Table  showing  the  effect  of  reduced  and  unreduced 
phosphates  on  cotton  in  1873,  at  Athens,  Georgia: 

1st           2d           3d  Tr-_  _ 

Fertilizers.      Amount.      Pick-       Pick-      Pick-      Total.  acre 
ing.         iiig.  ing. 

Lime.   53)^)  ^  ^  200  oz. .  .750 

Superpnospnate  o3><3 ) 

Lime  53J<^...75     ...62     ...43     ...180  ...675 

Superphosphate  533^ . .  101     ...  86     ...  50     ...  287  ...  887 

No  manure                         56     ...65     ...47     ...168  ...600 

From  the  above  experiment  it  is  seen  that  while  the 
lime  by  itself  increased  the  product  over  the  natural  soil 
twelve  ounces,  it  reduced  the  amount  made  by  the  super- 
phosphate 37  oz.  by  throwing  it  back  into  the  tri-basic 


300 


FERTILIZEES  AND  NATURAL  MANURES. 


form.  This  teaches  very  clearly  that  lime  and  superphos- 
phates are  incompatible,  and  that  it  will  not  pay  to  apply 
the  latter  to  soils  abounding  in  lime. 

267.  Ammo7iiated  Superphosphate, 

We  have  seen  that  nitrogen  and  phosphoric  acid  are 
the  first  principles  exhausted  from  the  soil;  hence,  when  ap- 
plied in  soluble  conditions,  they  act  as  powerful  fertilizers. 
In  order,  however,  for  them  to  act  efficiently,  .they  must 
be  applied  together.  Nitrogen  by  itself,  or  phosphoric  acid 
by  itself,  will  produce  only  partial  results,  especially  in  the 
production  of  seeds.  Combine  them,  and  marked  results 
will  follow. 

In  1867,  we  applied  superphosjohates  alone  on  cotton, 
at  the  rate  of  178  lbs.  to  the  acre,  and  75  lbs.  of  Peruvian 
guano,  combined  with  as  much  superphosphate.  The  for- 
mer produced  633  lbs.  of  seed  cotton,  the  latter  907. 

In  1869  we  used  the  sulphate  of  ammonia  and  super- 
phosphate, each  alone,  and  then  the  two  combined,  at  a 
cost  of  $10  each  per  acre,  with  the  following  result: 

l^t  2d  3d         4th       ,p  ,  ,  Increased 

Picking.  Picking.  Picking.  Picking.  product. 

Ammonia  20  47  35  6  108  19}^  lbs 

Superphosphate  21  62  37  7. ...  ,129  393^  " 

Combined  57  83  11  1  152  75  " 

The  last  column  indicates  the  increased  production  ovei 
the  natural  soil,  showing  that  a  combination  of  nitrogen  and 
phosphoric  acid  is  much  more  powerful  in  the  production  of 
cotton  at  least,  than  when  taken  separately. 

In  1870  we  applied  the  same  fertilizers  to  cotton  in 
similar  proportions,  in  rows  70  yards  long  ;  the  ammo- 
niated  phosphate  made  287,  the  superphosphate  alone  204 
oz.,  the  natural  soil  118  oz. 

The  following  table  of  an  experiment  in  1873,  shows 
still  further  the  effect  of  combination,  though  not  so  marked 


am:moxiated  superphosphate. 


301 


as  some  of  the  other  experiments.  The  cotton  was  planted 
m  rows  seventy  yards  long.  The  natural  soil  is  the  average 
of  six  rows  on  each  side  of  the  plot. 


Amount  per  Acre. 

1st 
Pick- 

2d 
Pick- 

3d 
Pick- 

4th 
Pick- 

Total. 

Lbs.  per 
acre. 

ing. 

ing. 

ing. 

ing. 

Pure  Ammonia,  22  lbs.. . 

46  oz, 

.  .97  oz. 

.  54  oz . 

.  8oz. 

.205  oz. 

.750  lbs. 

Pure   Bi-pliospliate  of 

Lime,  66  lbs  

20  . 

..90  . 

.78  . 

.14  . 

.202  . 

.742 

Six  lbs.  Ammonia,  42  lbs 

56  , 

.119  . 

.60  . 

.  6  . 

.231  . 

.866 

14  . 

.65  . 

.60  . 

.15  . 

.154  . 

.562 

The  ammonia  was  used  in  the  form  of  sulphate,  and  of 
course  had  sulphuric  acid  besides  the  pure  ammonia.  The 
bi-phosphate  was  used  as  a  superphosphate,  and  the  com- 
pound had  ammonia  potential  and  actual,  combined  with 
superphospliate.  The  bi-phosphate  cost  something  less  than 
the  other  two  per  acre. 

Peruvian  guano,  which  has  proven  to  be  so  powerful  a 
fertilizer  for  all  agricultural  crops  in  every  soil  and  climate, 
is  itself  a  remarkable  combination  of  nitrogen  and  phos- 
phoric acid,  while  the  latter  is  to  a  large  extent  insoluble 
as  found  in  the  dry  guano.  When,  however,  it  becomes 
moist  in  the  soil,  a  decomposition  takes  place  through  the 
agency  of  the  sulphate  of  ammonia,  by  which  the  bone 
phosphate  of  lime  is  transposed  into  oxalate  of  lime  and 
phosphate  of  ammonia.  The  phosphoric  acid  then  becomes 
soluble,  diffusing  itself  through  the  soil,  and  forming  solu- 
ble combinations  of  potash,  phosphate  of  soda,  and  phos- 
phate of  ammonia.  (Liebig.)  This  substance  then,  is  the 
most  remarkable  of  all  combinations,  natural  or  artificial  as 
to  fertilizing  qualities.  The  advantage  of  manipulated  fer- 
tilizers over  it,  is  because  they  contain  the  minimum  of 
ammonia,  and  are  cheaper  and  less  heating,  requiring  less 
rain  for  the  crops. 

A  good  formula  would  embrace  about  three  per  cent. 


302 


FERTILIZERS  AND  NATURAL  MANURES. 


of  ammonia  and  nine  of  soluble  phosphoric  acid,  equal 
to  19.50  of  bi-phosphate  of  lime.  The  remainder  of  the 
hundred  pounds  being  made  up  of  alkaline  salts,  insoluble 
phosphate,  sulphate  of  lime,  organic  matter,  and  a  small 
percentage  as  necessary  concomitants  of  alumina,  iron,  and 
silica. 

While  most  commercial  fertilizers  are  of  a  lower  grade 
than  this,  there  are  no  well-established  houses  who  would 
attempt  to  palm  off  a  spurious  article  on  the  farmers.  It 
would  take  but  one  year  for  such  an  article  to  be  condemned 
by  experiments  in  the  field,  to  say  nothing  of  the  labora- 
tory. 

^     CHAPTER  YI. 

POTASH,  SODA,  AND  LIME,  AND  THEIR  COMPOUNDS, 
MAGNESIA,  SULPHURIC  ACID,  CHLORINE. 

268.   Potassa^  KO. 

Next  to  phosphoric  acid,  potash  or  potassa  is  the  most 
valuable  inorganic  ingredient.  Its  symbol  is  KO,  having 
one  equivalent  of  potassium  (kalium)  and  one  of  oxygen. 
Potassa  is  the  technical,  potash  the  commercial  name. 

The  potash  of  commerce  is  a  hydrated  oxide  of  potas- 
sium, and  is  not  valued  much  as  a  fertilizer.  Twenty  years 
ago,  agricultural  chemists  were  much  concerned  about 
using  potash  in  some  form,  as  they  thought  Peruvian 
guano  would  exhaust  the  soil  of  this  important  substance  ; 
and  yet  it  could  not  be  used  in  conjunction  with  ammonia 
or  superphosphate,  causing  the  one  to  escape  and  the  other 
to  be  thrown  back  into  a  neutral  phosphate.  Hence  a  pre- 
paration was  made  and  sold  in  Baltimore,  by  Mr.  Samuel 
Sands,  of  plaster  and  potash,  containing  10  per  cent,  of  the 
latter. 

We  tested  it  in  1867,  applying  187  lbs.  per  acre,  at  a 


CHLORIDE  OF  POTASSIUM. 


303 


cost  of  $4.20,  in  rows  of  cotton  70  yards  long,  on  a  clay 
soil.  It  produced  at  the  rate  of  646  lbs.  of  seed  cotton, 
against  578  of  natural  soil,  not  making  enough  within  60  c. 
to  pay  for  its  purchase.  The  second  year,  however,  it  did 
much  better  in  the  same  rows,  having,  as  we  suppose,  been 
converted  into  a  carbonate  by  the  action  of  carbonic  acid 
in  the  soil,  as  well  as  by  reducing  the  organic  and  mineral 
substances  of  the  soil  to  an  assimilable  condition. 

269.    Chloride  of  Potassium, 

The  chloride  of  potassium  shipped  from  Germany,  is 
now  the  cheapest  and  most  reliable  form  in  which  potash 
is  used.  Especially  is  it  considered  valuable  in  the  pro- 
duction of  tobacco  on  the  worn  soils  of  Virginia.  In  1870, 
we  made  an  experiment  with  this  substance  on  a  poor  clay 
soil,  near  Sparta,  and  also  with  the  dung  salt,  a  German 
compound,  containing  potash,  soda,  sulphuric  acid,  chlorine, 
magnesia,  and  lime.  Both  of  these  preparations  produced 
considerable  weed,  giving  the  promise  of  a  bountiful  har- 
vest, so  that  a  casual  observer  would  have  pronounced  it  a 
success,  but  the  result  was,  of  the  chloride  of  potassium, 
373  lbs.;  dung  salt,  352  lbs.;  natural  soil,  348  lbs.  of  seed 
cotton  per  acre. 

In  1873,  we  instituted  the  following  experiment  on  a 
worn  clay  soil:  53^  ounces  of  each  of  the  salts  below  were 
applied  to  a  row  of  cotton  70  yards  in  length.  Six  rows 
on  each  side  with  natural  soil  averaged  162  oz.  The  salts 
produced  above  this  the  following  amounts: 

Sulph.  soda.  . .  .39  oz.  Nit.  potash  11  oz. 

Sulph.  lime  39  "  Sulph.  magnesia.  .8  " 

Nit.  soda  15  Chloride  potassa.  .6  " 

All  combined  .  .49  "  Chloride  sodium.  .1  "  less. 

Another  experiment,  in  which  a  formula  containing 
superphosphate,  ammonia,  animal  matter,  and  chloride  of 
sodium  was  used  in  the  one  row,  with  6f  oz.  chloride  of 


304 


FERTILIZERS  AND  NATURAL  MANURES. 


potash  added,  and  in  an  adjoining  row  the  same,  only  an 
equal  quantity  of  sulphate  of  soda  was  added,  with  the 
following  results  : 

Formula  with  potash  211  oz. 

"    soda   194 

Natural  soil  131  " 

In  this  case,  the  muriate  of  potash  in  combination  beat 
the  sulphate  of  soda,  but  its  cost  being  more  than  double, 
still  renders  it  an  unsafe  investment. 

In  another  experiment  on  the  poorest  spot  in  the  farm, 
we  applied  under  rows  of  cotton  54  yards  long,  40  ozs. 
superphosphate,  and  12  of  sulphate  of  ammonia,  adding  for 
one  row  12  oz.  of  muriate  of  potash,  and  for  the  other  row 
12  oz.  sulj^hate  of  soda,  with  the  following  results  : 

Formula  with  mur.  potash  211  oz. 

sulph.  soda  162  " 

Natural  soil  62  " 

From  this  experiment,  we  infer  that  a  sufficiency  of 
ammonia  and  phosphoric  acid  greatly  enhances  the  value 
of  potash  on  very  poor  soil  in  the  production  of  cotton. 

270.   Soda,  Na-0. 

Soda  is  not  very  abundant  in  soils,  but  is  generally 
present  in  sufficient  quantities  to  supply  the  demand. 
Even  where  it  is  partially  absent,  it  is  believed  that  pot- 
ash will  supply  its  place,  as  they  are  both  alkalies,  and 
possess  in  common  the  same  properties. 

It  has  been  surmised  by  some  that  soda  is  not  indispen- 
sable to  plant  life,  and  that  its  presence  in  plants  is  only 
accidental.  Herdpath  found  in  tAVO  analyses  of  asparagus 
and  beet  as  follows : 


Wild  asparagus  Potash.  .18.8  Soda.  .16.2 

Cultivated''     50.5....    "  ..trace 

Field  beet,  No.  1   "....57.0....    "  ...7.3 

No.  2   "  21.0          "  .  .34.1 


SODA. 


305 


Here,  there  is  15  per  cent,  more  of  alkalies  in  the  culti- 
vated than  in  the  wild  asparagus,  which  must  have  been 
accidental,  as  both  were  perfect  plants;  and  the  ]30tash 
and  soda  vary  considerably  in  both  the  asparagus  and  beet, 
showing  that  they  are  to  a  large  extent  interchangeable  ; 
and  as  in  one  instance  there  is  a  trace  of  soda,  ^v^here  it 
replaces  the  potash  it  must  be  accidental;  and  the  replaced 
potash  must  also  be  accidental,  or  the  soda  answers  the 
same  end  of  the  potash.  Evidently,  the  quantities  of  al- 
kalies taken  up  by  plants,  depend  to  a  large  extent  on 
the  amount  assimilable  in  the  soil. 

From  experiments  of  Salm-Horstmar,  Knop,  and  Schre- 
ber,  they  conclude  that  soda  cannot  entirely  replace  potash, 
the  latter  being  indispensable  to  plant  life.  Cameron  has 
satisfied  himself  from  a  series  of  experiments,  that  soda  can 
partially  replace  potash  in  plants. 

The  range  of  alkalies  is  very  great  in  plants.  Thus  in 
79  analyses  of  wheat  kernel,  the  highest  percentage  of  soda 
was  15.9,  the  lowest  0.0  per  cent.  In  21  analyses  of  rye, 
the  highest  was  20.8  ;  the  lowest  0.0.  In  barley,  43  ana- 
lyses, the  highest  was  8.9  ;  the  lowest  0.6.  In  14  analyses 
of  Indian  corn,  the  highest  13.2  ;  the  lowest  0.0.  Although 
soda  is  put  down  as  absent  in  most  of  these  cases,  it  does 
not  appear  that  the  specimens  were  all  perfect  seed,  or 
that  it  was  absent  from  the  entire  plant.  Under  the  older 
modes  of  analysis  it  was  difficult  to  separate  traces  of  soda 
from  potash,  and  it  is  possible  that  in  all  cases  it  is 
present. 

From  the  most  recent  analyses  made  by  experts,  soda 
exists  in  the  ash  of  certain  plants  as  follows  : 

Asli  of  wheat  kernel 
Potato  tuber  . . . 
"    Barley  kernel  .  . 

"    Sugar  beet  

"    Turnip  root .... 


,0  to  5  per  cent. 
0to4  " 
ItoG  " 
4.7  to  29.8  per  cent. 
7.7  to  17.1  " 


306 


FERTILIZERS  AND  NATURAL  MANURES. 


The  result  of  all  the  investigations  shows  very  clearly, 
that  while  soda  may  not  exist  in  some  cereals  and  tubers 
in  a  weighable  quantity,  yet  all  plants  have  traces  of  it, 
and  that  it  is  indispensable  to  plant  life.  The  newly  dis- 
covered spectral  analysis  by  which  yo~ooVo o o o  ^  grain 
of  soda  may  be  detected,  shows  that  it  exists  in  everything 
in  nature,  however  minute. 

From  a  number  of  experiments,  Salm-Horstmar  con- 
sidered soda  not  essential  in  the  early  stages  of  plants,  but 
important  to  their  perfection,  though  in  small  quantities. 

The  following  conclusions  seem  to  be  legitimate  from  all 
the  experiments  made:  1.  That  soda  is  never  entirely  ab- 
sent from  plants.  2.  That  it  exists  in  variable  proportions 
from  very  minute  to  large  quantities.  3.  That  only  minute 
amounts  are  requisite.  4.  That  when  it  exists  in  consider- 
able amounts,  it  is  rather  accidental  than  otherwise. 

While  some  of  the  German  experimentalists  have  satis- 
fied themselves,  that  soda  is  not  essential  to  buckwheat, 
and  other  plants,  we  have  in  an  experiment  the  present 
year  (1874),  not  yet  completed,  satisfied  every  one  who  has 
seen  it,  that  at  least  soda  is  very  essential. 

In  flower-pots  of  river  sand  out  of  which  all  soluble 
matters  had  been  thoroughly  washed  in  shoaly  water,  the 
pot  minus  the  soda  was  inferior  to  all  others  except  the 
ones  without  phosphoric  acid  and  potash ;  and  compared 
with  the  one  having  all  the  salts,  was  as  a  pigmy  to  a  giant. 

271.  Lime,  CaO. 

Lime  has  one  equivalent  of  calcium  =  20,  one  of  oxygen 
=  8.  It  is  then  an  oxide  of  calcium,  having  in  100  lbs.  71.43 
of  lime,  and  28.57  of  oxygen.  It  exists  in  all  soils  and  in 
all  plants. 

Lime  is  found  abundantly  in  nature  as  a  carbonate, 
from  the  coarsest  limestones  to  the  finest  marble.  This  is 
taken  and  burned  in  kilns,  the  carbonic  acid  escaping, 


LIME. 


307 


leaving  the  lime  as  a  hot  caustic  substance,  in  hard,  concrete 
masses. 

Take  a  lump  of  quicklime  and  pour  water  upon  it, 
and  it  hisses,  swells  and  cracks,  and  falls  into  a  white  pow- 
der, under  high  heat.  The  Avater  unites  chemically  with 
the  lime,  forming  a  hydrate.  When  caustic  lime  slowly 
acquires  moisture  from  the  atmosphere,  and  falls  to  a  fine 
powder,  it  is  said  to  be  air-slaked.  It  acquires  carbonic 
acid  also,  losing  much  of  its  caustic  properties,  assuming 
its  original  form  as  a  carbonate  of  lime,  only  in  a  pulveru- 
lent state. 

Carbonate  of  lime  is  very  insoluble  in  water,  and  not 
valued  much  as  a  fertilizer.  Very  few  soils  are  so  deficient 
in  lime  as  to  require  it  to  be  added  as  food  for  plants.  In 
that  case  the  most  economical  method  is  to  use  it  as  a 
bi-phosphate,  the  phosphoric  acid  of  which  is  always  in 
demand. 

Quicklime  is  a  valuable  application  for  turfy,  boggy 
soils,  otherwise  unfit  for  agricultural  purposes.  It  dis- 
integrates the  soil,  decomposes  the  organic  matter,  and 
neutralizes  the  acid  which  has  accumulated  for  years  in 
the  luxurious  beds  of  humus.  It  has  the  effect  of  opening 
the  dense  cemented  structure  of  clay  soils,  by  which  the 
atmosphere  is  able  to  reach  a  much  greater  surface,  and 
the  water  to  penetrate  deeper.  In  many  cases  it  also 
destroys  worms  and  insects  hurtful  to  vegetation. 

In  Europe,  where  liming  lands  constitutes  an  impor- 
tant part  of  good  farming,  caustic  lime  is  carried  to  the 
fields,  put  up  in  heaps,  and  covered  with  earth.  A  few 
weeks  will  suffice  for  it  to  become  air-slaked,  and  fall  to 
pieces,  thus  being  made  fit  for  use. 

We  have  doubted  the  utility  of  applying  caustic  lime 
to  our  worn  soils,  already  denuded  of  organic  matter  by 
our  system  of  clean  cotton  culture.  At  the  North  and  in 
Europe,  where  organic  matter  accumulates  so  rapidly, 
lime  is  essential  as  a  corrective  and  solvent.    Even  there, 


308 


FEPwTILIZEES  AND  NATURAL  MANURES. 


objections  have  been  raised  in  some  instances,  because 
lands  are  said  to  become  jDOorer  and  poorer,  under  the 
constant  application  of  lime.  A  small  experiment  on  a 
worn  soil,  deficient  in  organic  matter,  has  made  us  think 
moie  favorably  of  it.  In  a  row  of  cotton  70  yards  long, 
we  put  10  lbs.  of  caustic  lime  under  the  seed  ;  in  another, 
42  lbs.  of  well-rotted  chip  manure  ;  in  a  third,  the  same 
quantity  of  lime  and  chip  manure;  and  in  a  fourth,  quad- 
ruple the  quantity  of  chip  manure.  The  product  of  each 
row  was  as  follows:  Chip  manure,  218  oz. ;  air  slaked  lime, 
236  ;  lime  and  chip  manure,  260 ;  chip  manure  quad- 
rupled, 292  ;  no  manure,  182. 

The  lime  by  itself  increased  considerably  the  produc- 
tion over  the  natural  soil,  showing  its  solvent  action 
mainly  on  the  mineral  matter  of  the  soil.  The  chip  ma- 
nure doubtless  was  enhanced  in  value,  by  nitrogenous  par- 
ticles accumulated  about  the  wood-yard. 

The  silicate  and  nitrate  of  lime  occur  sparsely  in  nature, 
and  are  believed  to  act  well  as  fertilizers  ;  but  we  are  satis- 
fied that  no  form  of  this  important  substance  need  ever 
be  applied  as  mere  food  for  plants,  except  the  superphos- 
phate. This  embraces  the  soluble  bi-phosphate  and  the 
sulphate — the  one  very  soluble,  and  united  to  the  most  im- 
portant of  all  the  mineral  substances  needed  in  fertiliza- 
tion ;  and  the  other  a  good  absorbent  of  ammonia. 

272.  Sulphate  of  Lime,  CaO,S032HO. 

Sulphate  of  lime,  or  gypsum,  known  in  commerce  as 
plaster  of  Paris,  is  a  very  cheap  and  useful  form  for  appli- 
cation, under  some  conditions.  It  exists  in  nature  in 
many  localities,  amorphous  and  crystallized,  and  is  found 
in  the  ashes  of  many  plants,  as  clover,  beans,  etc.  The 
water  is  driven  out  by  burning,  forming  plaster  of  Paris. 
Ii  exists  very  sparsely  in  soils,  and  is  but  slightly  soluble 
in  water.    It  is  found  in  superphosphates  from  40  to  50 


SULPHURIC  ACID  AS  A  FEETILIZEE. 


309 


per  cent.,  and  this  is  much  the  cheapest  form  for  its  appli- 
cation. It  is  used  very  extensively  in  some  sections  for 
clover,  and  is  believed  to  be  very  nsefal. 

Liebig  attributes  its  special  virtue  as  a  top  dressing  to 
the  fixation  of  ammonia,  which  being  brought  down  by  dew 
and  rain,  displaces  the  lime,  forming  a  sulphate  of  am- 
monia— its  carbon  uniting  with  the  lime.  This  salt  being 
very  soluble  and  not  volatile  as  the  carbonate,  is  carried 
down  to  the  roots  of  the  clover  by  the  rains. 

213.  3Iagnesia^  MgO. 

Magnesia,  the  oxide  of  magnesium,  occurs  in  the  shops 
as  calcined  magnesia,  and  is  found  in  the  ashes  of  all 
plants  ;  and  is  universally  difiused  through  all  soils. 

Magnesia  exists  largely  in  the  grain  of  the  cereals  and 
other  agricultural  plants,  standing  next  to  phosphoric  acid 
and  potash.  This  shows  its  importance.  Arandt  found 
that  it  is  translated  from  the  lower  to  the  upper  organs  in 
the  oat,  and  that  it  increases  constantly  in  the  fruit. 

Liebig  states  that  the  bran  of  flour  contains  a  large 
quantity  of  ammoniacal  jDhosphate  of  magnesia.  This 
salt  often  forms  large  crystalline  concretions  in  the  large 
intestines  of  horses  belonging  to  millers ;  and  ammonia 
mixed  with  beer  causes  a  white  precipitate  of  the  same 
salt. 

Sulphate  of  magnesia,  the  only  form  in  which  we  used 
it  on  cotton  in  the  present  year  in  rows  70  yards  long, 
only  increased  the  product  from  160  natural  soil,  to  170  oz. 
Nevertheless,  we  think  a  complete  fertilizer  should  have  a 
small  quantity  in  it  for  most  of  our  worn  soils. 

274.  Sulphuric  Acid  as  a  Fertilizer, 

Sulphuric  acid  has  already  been  described.  It  is  an 
essential  element  of  plant-food,  although  not  existing 
largely  in  them,  yet  on  account  of  its  sparsity  in  all  soils 


310 


FERTILIZERS  AND  NATURAL  MANURES. 


should  be  introduced  in  all  first-class  fertilizers.  Luckily, 
for  agriculturists,  it  exists  in  very  cheap  forms,  as  sul- 
phate of  soda,  sulphate  of  lime,  sulphate  of  iron,  etc. 

Sulphuric  acid  forms  an  important  class  of  salts  called 
sulphates,  some  of  which  exist  as  such  in  the  ash  of 
plants. 

From  experiments  made  on  the  oat  plant,  Arandt  came 
to  the  conclusion  that  sulphuric  acid  is  formed  in  the 
upper  part  of  the  plant  by  the  oxidation  of  sulphur.  The 
albuminoids  cannot  be  produced  without  it,  as  sulphur  is 
a  necessary  constituent  of  them,  and  sulphuric  acid  is  the 
only  form  in  which  it  can  be  introduced  into  plants.  Cer- 
tain oils  found  in  onions,  mustard,  horse-radish,  turnips, 
etc.,  always  contain  sulphur. 

The  highest  percentage  of  sulphuric  acid  found  in  the 
ash  of  wheat  in  79  analyses  was  2.4,  the  lowest  0.0.  In 
21  analyses  of  rye,  the  highest  was  3.0,  loAvest  0.5.  In  43 
analyses  of  barley,  the  highest  was  4.0,  the  lowest  0.2. 
In  11  of  maize,  the  highest  was  5.5,  the  lowest  0.0. 

As  there  is  always  a  sufficiency  of  sulphuric  acid  in 
superphosphates  for  all  fertilizing  purposes,  there  is  no 
need  of  applying  it  except  in  this  form,  which  costs  abso- 
lutely nothing ;  as  it  is  a  necessary  concomitant  of  the 
phosphoric  acid  so  important  to  be  applied  at  almost  any 
cost. 

275.    Chlorine,  CI. 

Chlorine  exists  very  sparingly  in  soils  and  in  jjlants,  but 
is  nevertheless  deemed  to  be  important. 

A  weak  solution  of  chlorine,  Humboldt  asserts,  wdll  fa- 
cilitate the  sprouting  of  seeds.  As  suggested  by  Johnson, 
no  doubt  a  reaction  takes  place  by  which  water  is  decom- 
posed and  oxygen  set  free,  which  is  doubtless  the  real  agent 
in  exciting  the  sleeping  germ. 

Chloride  of  potassium  is  present  in  the  juices  of  all 
plants  as  well  as  their  ashes,  especially  sea-w^eeds  ;  and  is 


CHLORIDE  OF  SODIUM  AS   A  FERTILIZER. 


311 


never  absent  from  fertile  soils.  The  same  is  essentially 
true  of  chloride  of  sodium.  And  yet  some  scientists  seem 
to  doubt  whether  it  is  indispensable  to  the  life  and  perfec- 
tion of  plants. 

Salm-Horstmar,  Nobbe,  and  Siegert  consider  it  essen- 
tial to  the  production  of  wheat.  Knop  excludes  it  from 
maize,  and  considers  its  importance  to  buckwheat  as  doubt- 
ful. Leydhecker,  from  recent  investigations,  regards  it, 
however,  as  indispensable  to  buckwheat.  Birner  and  Lu- 
canus  conclude  that  it  is  not  necessary  to  the  oat  plant. 
The  weight  of  the  crop  w^as  increased  by  chloride  of  potas- 
sium, the  foliage  and  stem  by  chloride  of  sodium,  while 
chloride  of  magnesium  proved  deleterious  to  the  plant. 
Lucanus  raised  a  perfect  crop  of  clover  without  chlorine, 
and  when  added  the  result  was  not  increased. 

While  it  is  true  that  chlorine  is  always  present  in  plants, 
much  that  appears  in  the  foliage  and  succulent  parts  is  ac- 
cidental. Nevertheless,  until  more  conclusive  experiments 
have  been  made,  we  must  conclude  that  it  is  essential, 
though  in  minute  quantities,  to  most  agricultural  plants. 

In  70  analyses  of  wheat,  the  highest  was  6.1,  the  lowest  .0 


43 

barley,  " 

5.2, 

"  .2 

21 

rye, 

2.5, 

"  .0 

21 

oat,  " 

1.6, 

"  .0 

11 

maize,  " 

4.5, 

"  .0 

31 

pea. 

6.5, 

"  .0 

3 

cotton  seed,  " 

4.8, 

"  .5 

276.    Chloride  of  Sodium  as  a  Fertilizer. 

Prof.  Voelcker  is  of  opinion  that  common  salt  has  the 
power  of  liberating  ammonia  from  soils  that  have  been 
manured  with  Peruvian  guano,  stable  manure,  etc.  This 
is  true  especially  in  sandy  soils  where  the  ammonia  exists 
in  fertile  combinations.  The  chloride  of  sodium  acts  upon 
the  ammoniacal  salts  by  forming  soda  in  the  soil,  and  chlo- 


312 


FERTILIZERS  AND  NATURAL  MANURES. 


ride  of  ammonia,  which  passes  into  solution  and  then  be- 
comes an  active  fertilizer. 

This  throws  light  on  the  use  of  salt  as  a  fertilizer.  It 
is  known  that  on  poor  lands  devoid  of  humus  and  ammo- 
nia, it  is  a  very  indifferent  manure,  while  on  better  lands, 
w^here  ammonia  has  been  stored  in  the  clay  or  humus,  it 
acts  well  by  eliminating  the  ammonia  and  placing  it  in 
combinations  suitable  for  plant  nutriment. 

Salt  is  also  beneficial  in  soils  as  fertilizers,  by  aiding 
in  rendering  insoluble  phosphates  soluble.  We  suppose 
chlorhydric  acid  is  set  free,  which  dissolves  the  bone  phos- 
phate and  transforms  it  into  a  soluble  by  phosphate  of 
lime. 


CHAPTER  YII. 

NATURAL  MANURES. — STABLE  MANURE.  NIGHT  SOIL. 

COTTON  SEED.  WOOD  ASHES. 

277.  Natural  3Ianures. 

We  shall  embrace  in  what  we  term  natural  manures 
all  those  substances  produced  on  a  farm,  which  by  proper 
treatment  and  application  aid  in  the  growth  of  plants  and 
the  improvement  of  the  land  ;  as  well  as  those  resulting 
from  processes  in  nature  known  to  the  intelligent  agricul- 
turist, which  subserve  the  same  end. 

To  the  first  class  properly  belong  farm-yard  manure, 
night  soil,  and  cotton  seed:  to  the  last,. green  manures  and 
rotation  of  crops. 

278.  Stable  Manure, 

Farm-yard  or  stable  manure  is  a  powerful  fertilizer, 
owing  mainly  to  the  amount  of  ammonia  it  contains.  It 
nevertheless  has  all  of  the  other  important  elements  and 


co:viPOsrnox  of  stable  maxure. 


313 


salts,  though  in  undue  proportions.  It  is  especially  defi- 
cient in  phosphoric  acid,  so  essential  to  the  grains  of  the 
cereals,  and  the  seed  of  cotton.  It  is  also  very  heating  in 
its  character,  requiring  in  our  warm  climate  more  rain 
than  generally  falls.  Hence  it  should  always  be  composted 
and  modified  when  applied  to  crops. 

This  important  manure  consists  of  the  urine  and  solid 
excrements  of  domestic  animals  mixed  with  various  kinds 
of  litter.  The  most  valuable  part  is  the  urine,  which  con- 
tains most  of  the  nitrogen  of  the  food  of  animals  ;  hence 
the  importance  of  having  materials  mixed  with  it  which 
will  hold  it  for  future  use.  When  urine  decomposes  in  a 
dung  heap  or  bed  of  litter,  its  ammonia  does  not  escape  as 
under  ordinary  circumstances. 

As  the  nourishing  quality  of  food  depends  greatly  on 
the  amount  of  nitrogen  in  it,  so  to  a  large  extent  is  the 
value  of  manures  enhanced  by  the  amount  of  nitrogen  in 
them.  The  nitrogen  present  in  urine  exists  as  urea,  uric 
acid,  and  hippuric  acid,  but  these  compounds,  by  sponta- 
neous decay,  all  form  ammonia,  which  will  escape  unless 
proper  means  are  taken  to  prevent  it.  Hence  ammonia 
has  been  found  always  existing  in  the  atmosphere  of 
stables. 

Other  compounds  are  also  present  in  urine  of  great 
value,  especially  phosphoric  acid  and  potash,  which  exist 
to  a  large  extent  in  soluble  forms.  In  1,000  parts  of  urine 
from  the  stable  there  are  890  of  water,  16  of  ammonia  as 
nitrogen,  and  1.20  of  phosphoric  acid.  In  solid  horse-dung 
there  are  760  of  water,  6.10  of  ammonia  as  nitrogen  and 
3.48  of  phosphoric  acid. 

279.    Composition  of  Stahle  Manure. 

The  following  table  will  show  the  analysis  of  two  fair 
samples  of  farm-yard  manure,  by  Voelcker. 
14 


814 


FERTILIZERS  AND  NATURAL  MANURES. 


Fresh.  Rotted. 


Water  66.17  75.42 

SoluWe  organic  matter,  *  2.48  3.71 

Insoluble  organic  matter,  f  25.76  12.82 

Soluble  salts  1.54  1.47 

Insoluble  mineral  matters  4.05  6.58 


100.00 


100.00 


*  Containing  nitrogen 

t 


Free  ammonia  . . . 
Amnion iacal  salts 


,0.149, 
.0.494 
,0.340. 
0.880. 


,0.297 
.0.309 
0.046 
0.057 


The  fresh  manure  contains  0.299  soluble  phosphate  of 
lime,  and  the  rotted  0.832.  Of  potassa,  the  first  contains 
0.573  soluble,  and  0.446  insoluble.  In  addition,  they  have 
also  lime,  silica,  soda,  chlorine,  sulphuric  acid  and  carbonic 
acid,  soluble  and  insoluble. 

In  100  lbs.  then  of  good  farm-yard  manure,  we  have 
when  fresh,  1.863  lbs.  of  nitrogen.  As  14  of  nitrogen  is 
equal  to  17  of  ammonia,  the  actual  ammonia  in  fresh  stable 
manure  is  2.001,  in  rotted  manure  0.839.  Of  course  it 
varies  greatly,  according  to  the  kind  of  food  used,  and  the 
process  of  saving  it. 

The  great  virtue  of  stable  manure  is  in  its  nitrogen, 
and  we  perceive  that  a  great  loss  is  sustained  by  the  rot- 
ting process,  more  than  one-half  of  the  ammonia  having 
escaped.  How  can  this  be  saved  to  the  farmer,  so  as  to 
secure  the  greatest  profits  ?  There  is  no  question  that  for 
immediate  action,  well-rotted  manure  is  the  best,  though 
having  less  nitrogen. 

280.   Savi7ig  and  Composting  3Ianures. 

In  a  cotton  country,  Avhere  stock  is  a  secondary  object, 
we  cannot  expect  to  depend  much  on  farm-yard  manure^ 
and  yet  enough  might  be  made  for  the  near  fields,  by 
proper  economy,  from  the  mules  and  milch  cows  of  a  cot- 


SAVING  AXD  COMPOSTING  MANURE. 


315 


ton  plantation.  In  order  to  this,  have  comfortable  covered 
and  separate  stalls  for  all  of  your  stock.  Cover  the  floor 
for  several  inches  thick  with  dry  chip  manure,  pine  straw, 
oak  leaves,  or  other  litter.  As  it  becomes  saturated  with 
urine  and  excrement,  add  more,  so  as  to  keep  a  dry  bed 
for  the  cattle  to  stand  or  lie  on.  Occasionally,  it  is  proper 
to  reverse  the  position  of  the  central  and  saturated  portions, 
and  the  untrodden  outside  part.  Much  litter  also  accumu- 
lates in  the  course  of  the  year,  from  the  refuse  of  the 
fodder,  straw,  cobs,  etc. 

The  stalls  should  never  be  touched  until  after  Christ- 
mas, as  they  accumulate  and  hold  most  of  the  valuable 
salts  by  this  process.  Then  break  up  and  chop  into  small 
pieces  the  accumulated  mass,  and  make  your  compost 
heaps,  as  follows:  A  layer  of  stable  manure  six  inches 
thick,  with  a  good  sprinkling  of  superphosphate  over  it ; 
then  a  layer  of  cotton  seed  three  inches  thick  {previously 
saturated  with  water),  and  then  another  sprinkling  of 
superphosphate,  say  half  an  inch  thick ;  then  a  layer  of 
stable  manure,  and  so  on  until  the  heap  is  completed,  which 
should  be  conical  in  form.  Over  the  whole  heap,  when 
sufficiently  large,  apply  several  inches  of  dry  clay  soil,  if 
you  choose,  which  will  absorb  every  particle  of  the  escap- 
ing ammonia.  If,  however,  this  crust  should  become  so 
saturated  as  to  allow  it  to  escape,  you  can  easily  deter- 
mine the  fact  by  moistening  a  piece  of  red  litmus  paper, 
and  holding  over  the  surface  at  different  points;  the 
smallest  escape  of  ammonia  will  change  the  red  to  blue, 
and  an  additional  coating  of  soil  can  be  applied. 

The  heaps  should  be  put  up  soon  after  Christmas,  and 
not  touched  till  ready  to  put  into  the  corn  or  cotton  beds  in 
March  and  April.  In  the  mean  time  the  stalls  should  be 
replenished,  and  not  touched  again  for  twelve  months, 
only  in  the  way  indicated  above.  When  the  manure  is 
hauled  out,  every  layer  in  the  heaps  should  be  chopped 


316 


FERTILIZERS  AND  NATURAL  MANURES. 


down  and  well  mixed  and  pulverized.  It  should  be  taken 
from  wagons  and  carefully  applied  in  baskets  at  the  rate 
of  five  or  six  hundred  pounds  to  the  acre,  at  the  bottom  of 
a  shovel  furrow  and  then  bedded  on  immediately.  Th6 
best  results  would  follow^ 

This  is  the  best  process  known  to  manufacture  farm- 
I  yard  manure,  as  adapted  to  our  circumstances.  By  this 
you  save  all  of  the  valuable  elements  of  dung  and  urine, 
converting  the  nitrogen  into  ammonia  for  prompt  and 
efficient  action  the  first  year,  and  relieving  the  manure  to 
a  lg,rge  -extent  of  the  heavy  masses  of  water  found  in  this 
class  of  manures.  You  also  kill  the  germ  of  your  cotton 
^^eed,  and  have  its  nitrogen  converted  into  ammonia  in- 
stead of  lying  out  exposed  to  the  leaching  rains  and  evap- 
orating winds  of  winter.  Enough  soluble  phosphoiic 
acid  is  also  added  to  supply  a  deficiency  in  'both  of  the 
other  manures.  We  are  satisfied  that  such  a  mixture  will 
pay  better  than  any  other  for  the  same  cost.  And  the 
whole  plan  is  adapted  to  scarcity  of  labor,  as  there  is  the 
least  possible  expense  attending  it,  being  handled  but 
once  before  it  is  ready  to  be  carted  to  the  fields.  Where 
much  litter  is  applied,  it  might  be  necessary  in  some  in- 
stances, to  compost  every  six  months,  but  we  believe  the 
other  plan  the  most  economical  of  the  two. 

Manures  should  not  lie  long  in  the  heap  after  decom- 
])Osition  has  taken  place.  As  they  become  weaker  gra- 
dually from  further  decay,  the  humus  which  absorbs  the 
ammonia,  itself  decays  slowly,  losing  its  carbonic  acid 
vrhich  unites  with  the  ammonia,  forming  a  very  volatile 
8:ilt ;  and  in  several  other  ways  this  deterioration  may  be 
carried  on  ;  hence  it  is  important  to  apply  it  early  to  the 
soil,  which  will  hold  it  much  better  than  the  compost 
lieap.  In  fact,  so  tenacious  are  clay  soils  of  ammonia 
and  other  salts,  that  it  is  probable  that  well  rotted 
manure  might  be  spread  on  the  top  of  the  ground,  and 


CHEMICAL  CHANGES  IX  MANUKE  HEAPS. 


SI*? 


lose  little  more  than  water  and  carbonic  acid  by  evapora- 
tion ;  all  of  the  valuable  salts  being  absorbed  by  the  soil 
or  leached  out  by  the  rains  into  it  are  ttius  as  safely  stored 
as  if  the  whole  of  the  manure  were  buried.  In  silicious 
soils,  however,  these  valuable  salts  are  soon  carried  down 
beyond  the  reach  of  the  rootlets,  hence  their  application 
should  be  made  at  the  latest  period  possible  in  such 
cases. 

Farm-yard  manure,  kept  in  open  yards,  will  in  the  , 
course  of  tv\^elve  months  lose  two-thirds  of  its  valuable  salts, 
leaving  little  else  than  stVaw  and  undecomposed  organic 
matter.  This  loss  is  mainly  produced  by  the  leaching  of 
the  rains  ;  though  the  w^inds  and  sun  carry  off  some  of  the 
valuable  volatile  matters. 

281.  \jhemical  Changes  in  Manure  Heaps, 

Chemically  considered,  farm-yard  manure  is  a  very  va- 
riable and  uncertain  mixture,  as  it  depends  on  so  many 
contingencies  ;  such  as  the  age  and  number  of  the  animals, 
their  breed,  condition  and  species,  the  quantity  and  qual- 
ity of  their  food,  and  of  the  litter  used  in  their  stalls.  The 
dung  of  a  poor  grass-fed  cow  or  horse  would  be  of  little 
value  compared  with  one  fed  on  highly  nutritious  hay  and 
grain.  A  great  degree  of  uniformity,  however,  might  be 
attained  on  a  single  farm,  by  a  continuous  and  regular 
process  as  to  feeding,  etc. 

Until  recently,  the  chemical  changes  which  take  place 
in  the  manufacture  of  farm-yard  manure  were  but  little 
understood.  Dr.  Yoelcker  found,  upon  analysis,  that  the 
prmcipal  difference  between  fresh  and  well  rotted  manure 
lies  in  the  amount  of  soluble  matters  contained  in  them. 
An  average  specimen  of  each  kind  (one  fourteen  days, 
and  the  other  six  months  old)  exhibited  the  following  re- 
sults : 


1               i'ERTILIZEES  A5^D 

NATURAL  MAXUEES. 

Freeh. 

Rotted. 

Soluble  organic  matter  

.2.48  perct... 

.  .  .  3.71 

per  ct. 

Containing  nitrogen  

.0.149  ... 

,  .,  ,2.97 

E(j[ual  to  ammonia 

.0.181      "  ... 

,  ,  ,  .  8  60 

Soluble  inorganic  matter  . . . 

.1.54       "   , . . 

, .  ,1.47 

t€ 

Of  whicL,  phosphate  of  lime 

.0.299 

. .  .0.382 

Potash  

.0.573      "  ... 

<i 

Ammonia  in  a  free  state. . . . 

.0.034      "  ... 

,  .  .0.046 

H 

form  of  salts  . . 

.0.088     "  .  . 

,    0  057 

t( 

Unassimilable  nitrogen  

.0.494     "  ... 

0.309 

(t 

.0.599  ... 

. .  .0  375 

(( 

From  this,  we  perceive  that  well  rotted  manure  is  more 
soluble  than  fresh  manure  as  5.18  is  to  4.02  ;  and  it  is  that 
much  more  valuable  ;  and  the  two  precious  articles  of  am- 
monia and  phosphoric  acid,  are  especially  soluble  in  the 
rotted  manure  ;  this,  in  fact,  constitutes  the  great  differ- 
ence between  them. 

It  might  be  useful  to  inquire  a  little  more  particularly 
into  the  chemical  changes  which  take  place  in  the  dung 
heap.  A  slow^  combustion  is  at  once  set  up  under  the  pro- 
cesses of  fermentation  in  the  non-nitrogenous  substances, 
such  as  straw,  corn  stalks,  etc.,  while  a  more  rapid  putre- 
factive process  transpires  in  the  nitrogenous  compounds  of 
the  urine  and  dung.  A  portion  of  the  non-nitrogenous 
matter  is  converted  into  carbonic  acid  and  water,  which 
escape,  while  the  larger  portion  is  changed  into  Immus, 
Tliis,  as  you  know,  is  the  black,  porous  substance  always 
formed  when  organic  matters  de^^ay,  and  upon  it  depends 
the  dark  color  of  well  rotted  dimg  and  rich  soils.  The 
])rincipal  portion  of  the  nitrogen  contained  in  the  urine  and 
dung,  is  by  this  putrefaction  at  once  changed  into  am- 
monia. This  being  so  very  volatile,  one  would  suppose 
that  it  would  escape  at  once  from  the  dung  heap.  Only 
a  small  portion,  however,  does  actually  escape,  as  can  be 
easily  ascertained  by  the  test  paper.  And  it  is  doubtful 
whether  it  is  necessary  to  use  any  chemical  means  to  cor- 


NIGHT  SOIL. 


310 


rect  or  absorb  it,  as  volatile  ammonia  is  only  formed  in 
the  interior  of  the  heap,  where  the  heat  is  highest,  and 
its  escape  is  prevented  by  the  humic  acid  and  other  sub- 
stances in  the  cooler  and  outer  portions  of  the  heap. 

Where  superphosphate  is  added,  the  sulphate  of  lime, 
and  in  some  instances  anhydrous  sulphuric  acid,  will  serve 
to  fix  it  as  a  sulphate  of  ammonia.  Thus  means  have  been 
provided  for  fixing  ammonia  simultaneously  with  its  pro- 
duction, at  least  during  the  process  of  fermentation  in 
compost  heaps.  Some  of  the  ammonia  of  the  dung  heap 
is  fixed  by  the  sulphuric  acid  which  results  from  the  sul- 
phur contained  in  the  manure,  being  formed  by  the  rapid 
decomposition  of  the  nitrogenous  compounds. 

The  mineral  substances  also  undergo  considerable 
changes,  the  principle  of  which  is  in  passing  from  insoluble 
to  soluble  conditions.  Phosphorus  and  sulphur  are  both 
required  in  the  production  of  flesh-forming  substances  ; 
and  are  always  present  in  the  fresh  excrements  of  animals, 
combined  in  certain  organic  principles.  They  are  broken 
up  by  putrefaction  and  enter  into  new  combinations,  two 
of  which  are  phosphuretted  and  sulphuretted  hydrogen 
gases.  They,  with  some  others,  constitute  the  peculiar  odor 
of  fermented  dung.  Whilst  minute  portions  of  sulphur  and 
phosphorus  escape  in  this  way,  the  great  bulk  is  found  in 
rotted  manure  as  phosphoric  and  sulphuric  acids. 

282.  Night  Soil 

There  are  other  sources  of  nitrogen  in  a  farm  yard, 
which  are  of  great  value,  which,  as  our  necessities  demand, 
and  we  become  more  economical,  will  be  utilized.  We 
refer  to  the  privy  and  the  chamber.  Human  excrement 
and  urine  are  among  the  most  powerful  fertilizers,  when 
properly  treated. 

Immense  waste  of  nitrogen,  as  well  as  other  valuable 
salts,  is  constantly  accruing  in  our  cities  and  towns,  which 


320 


FERTILIZERS  AND  NATURAL  MANURES. 


might  be  saved,  and  prove  an  immense  revenue  to  these 
corporations.  In  China,  every  particle  of  human  ordure 
is  saved  from  every  possible  source,  made  into  cakes,  dried 
in  the  sun,  ground  and  applied  to  the  crops.  When  we 
think  of  their  teeming  population,  v^e  can  well  perceive 
that  without  this,  the  lands  would  soon  be  exhausted  and 
the  country  depoj3ulated  by  famine  and  pestilence.  For 
the  very  process  of  saving  and  burying  their  excrement 
not  only  gives  them  bread,  but  purifies  the  atmosphere  and 
saves  them  from  malignant  fevers. 

The  French  manufacture  the  same  substance  into  a  fer- 
tilizer called  poudrette.  Other  cities  in  Europe  and  in  this 
country,  are  now  engaged  by  different  processes  and  com 
binations  in  manufacturing  a  similar  article.  That  made 
by  the  Lodi  Manufacturing  Company,  in  USTew  York,  and 
sold  at  about  a  cent  a  pound,  is  valuable  for  farms  and 
gardens  near  the  city,  but  will  not  pay  well  on  cotton,  as 
there  is  too  much  clay  used  in  the  drying  process  for  dis- 
tant transportation.  Much  of  this  valuable  manure  might 
be  prepared  and  saved  in  every  family,  but  for  a  foolish 
prejudice  among  all  classes  of  society  in  reference  to  -hand- 
ling and  using  it. 

The  best  method  yet  invented  is,  perhaps,  the  earth 
closet^  which  is  now  used  by  many  families  North,  even  in 
their  private  bed-rooms.  The  plan  is,  to  take  earth  abound- 
ing in  humus  and  clay,  dry  it  thoroughly  in  the  sun  or  by 
steam,  or  air-dry  it  in  a  room,  and  apply  daily  to  these 
closets  enough  to  cover  the  mass.  All  odor  is  prevented, 
and  every  particle  of  valuable  gas  secured  by  the  absorb- 
ing power  of  the  earth.  When  the  box  is  full  it  may  be 
taken  and  dried,  and  even  used  again,  until  thoroughly  sa- 
turated with  a  combination  of  valuable  soluble  salts.  This 
process  might  be  adopted  in  all  our  privies,  securing  at 
once  cleanliness  and  health,  and  a  most  valuable  fertili- 
zer. 


HUEDLING  SYSTEM. 


321 


283.  Hurdling  System, 

Much  of  the  nitrogen  and  other  elements  might  be  saved, 
in  a  small  way,  with  but  little  labor,  by  improving  on  the 
old  system  of  penning  cattle  at  night.  Our  fathers  used 
\  to  enrich  lands  in  this  way  to  make  turnips.  A  man  might 
prepare  a  number  of  acres  for  corn  or  cotton  in  the  same 
way. 

Fence  in  one  or  more  acres  on  your  exhausted  fields 
,  with  a  light  fence  near  the  homestead.  Here  pen  your 
cattle  at  night,  feeding  them  in  one  particular  spot  for  a 
while  and  then  move  the  troughs,  and  so  on,  until  the 
whole  lot  is  fertilized.  Then  move  one  angle  of  your  fence 
and  prepare  another  lot,  and  so  on.  You  might  thus,  in 
the  course  of  twelve  months,  fertilize  a  number  of  aci"es, 
according  to  the  amount  of  stock  on  the  farm.  In  the 
summer,  the  cat  tle  would  browze  during  the  day,  and  bring 
home  nitrogen  and  phosphoric  acid  and  potash  to  be  de- 
posited on  your  worn  soil  at  night.  In  the  winter  they 
could  be  kept  up  most  of  the  time  and  fed  on  rough  forage, 
and  pay  the  value  of  the  food  consumed,  twice  over.  Every 
man  would,  under  this  system,  see  the  value  of  stock  from 
a  new  stand-point,  and  gradually  increase  them  ;  which 
would  require  some  attention  and  some  labor  to  make 
food  for  them,  and  thus  lessen  the  cotton  crop  by  creating 
a  division  of  labor,  and  add  to  its  price,  thereby  increas- 
ing the  material  Interests  of  the  country. 

By  a  similar  process,  sheep  husbandry  might  be  a  great 
source  of  income  to  our  farmers.  There  is  nothing  more 
valuable  than  their  droppings  for  fertilizing  worn  soils, 
having  in  them  twice  as  much  nitrogen  as  fresh  horse  ma- 
nure, and  when  dry  as  three  to  two. 

By  a  recent  experiment  on  turnips,  we  have  become 
satisfied  that  any  amount  can  be  produced  on  aur  poorest 
soils  by  the  application  of  superphosphate.    50  lbs.  of  this 


322  FERTILIZERS  AND  NATURAL  MANURES. 


article,  costing  $1.25  per  acre,  with  half  a  stand  produced 
84  bushels;  the  natural  soil  only  21.  In  another  experi- 
ment, with  200  lbs.  of  ammoniated  superphosphate,  220^ 
bushels  were  produced,  against  52^  natural  soil. 

Now,  if  our  legislatures  would  tax  the  dogs,  and  the 
farmers  buy  a  little  superphosphate,  and  make  turnips  on 
land  otherwise  valueless,  having  a  small  flock  of  sheep  to 
begin  with,  they  could  do  several  good  things  thereby.  The 
sheep,  by  the  aid  of  hurdle  fences,  which  could  be  moved 
every  morning  if  necessary,  would  eat  the  turnips  ofi*  the 
land,  leaving  their  deposits  (which  would  enrich  the  soil), 
and  continue  during  the  winter  till  the  turnip  field  was  eat 
out,  then  you  have  a  rich  field  to  make  cotton  on,  with  a  crop 
of  wool,  and  a  supply  of  mutton.  If  all  would  engage  in  it, 
the  labor  is  divided  between  wool  and  cotton,  the  price  of 
cotton  advanced,  the  number  of  dogs  lessened,  and  more 
food  and  clothing  for  the  poor.  We  are  satisfied  that  wool 
can  thus  be  produced  cheaper  than  cotton,  and  know  that 
lands  can  thus  be  fertilized  at  a  much  cheaper  rate  than  to 
import  nitrogen  and  phosphoric  acid  from  the  Pacific  isles 
in  the  high  priced  guano  found  in  the  markets. 

Boussingault  made  an  experiment  with  200  sheep  on  a 
stubble,  for  one  fortnight.  He  found  that  each  sheep  ma- 
nured a  surface  of  four  yards  square  every  night,  so  as  to 
produce  a  maximum  crop  of  turnips.  At  this  rate,  a  flock 
of  200  sheep  would  make  26  acres  of  land  rich  in  one  year. 
Estimating  that  each  acre  would  make  600  lbs.  more  of 
seed  cotton  than  the  natural  soil,  the  200  sheep  would  make 
$780  at  15  cents  for  cotton  the  first  year;  and  the  second 
fifty  per  cent,  of  that  amount  could  be  realized  from  the 
same  land.  The  value  of  the  wool  and  mutton  would  be 
added  to  this.  What  an  immense  source  of  wealth  to  the 
country  sheep  husbandry  might  be  made,  if  this  plan  wa8 
carried  out ! 


COTTON  SEED  AS  A  MAXUEE. 


323 


284.   Cotton  Seed  as  a  Manure, 

Cotton  seed  has  already  been  mentioned  as  a  valuable 
nitrogenous  manure,  and  its  utilization  by  composting  with 
stable  manure  already  approved  and  described. 

The  mineral  elements  in  the  cotton  plant,  as  of  others, 
are  somewhat  diverse,  owing  to  the  difference  in  soil,  sea- 
sons, variety,  and  we  might  add,  the  method  and  skill  of 
the  chemist.  The  following  table  presents  eight  analyses 
of  five  chemists.  The  first  column  by  Prof.  Jackson  in- 
cludes the  average  of  four  analyses  of  upland  and  Sea  Island 
cotton  from  Georgia,  South  Carolina,  and  Mississippi.  M. 
Vi lie's  samples  were  from  Egypt. 

Table  showing  the  amount  of  each  constituent  in  1000 
parts  of  cotton  seed,  including  hull  and  kernel,  from 
analyses  of  six  different  chemists,  with  the  total  average. 

Higgins 


Land.  Jackson.  Villen.  Shepard. 

and 

White.  Average. 

Bickel. 

Pjiosphoric  Acid. 

.10.80. 

.10.08. 

.10.28. 

.13.45. 

.14.88.. 

.12.20.. 

.11.95 

Potash  

.12.74. 

.11.55. 

.  9.43. 

.10.56. 

.14.40.. 

.10.31.. 

.11.50 

Lime  

.  1.60. 

.  1.4G. 

.  7.76. 

.  4.14. 

.  2.48.. 

.  3.36.. 

.  3.46 

Magnesia  

.  5.40. 

.  6.64. 

.  4.21. 

.  4.02. 

.  5.68.. 

.  4.23.. 

.  5.01 

Sulphuric  Acid. . 

.  1.16. 

.  0.52. 

.  1.42. 

.  1.21. 

.  1.64.. 

.  2.20.. 

.  1.36 

Oxide  of  Iron. . . . 

.  0.38. 

.  0.53. 

.  1.25. 

.  0.24.. 

.  0.63.. 

.  0.60 

Chlorine  

.  0.17. 

.  0.39. 

.  0.40. 

.  1.82. 

.  0.20.. 

.  0.28.. 

.  0.54 

Soda  

.  0.29. 

.  4.13. 

.  0.77. 

.  1.02. 

.  0.44.. 

.  0.85.. 

.  1.25 

Silica  

.  0.39. 

.trace. 

,  0.39 

Here  we  have  a  powerful  fertilizer  containing  all  of  the 
organic  elements.  First,  the  ammonia,  then  carbon  and 
I  oxygen  to  combine  and  make  carbonic  acid,  which  in  its 
turn  would  render  soluble  the  phosphate  of  lime  of  which 
there  would  be  1.82  per  cent,  in  the  whole  seed,  with  small 
amounts  of  potash  and  soda  soluble  in  acids,  besides  chlo- 
j  rine,  sulphuric  acid,  etc. 

There  is  perhaps,  no  part  of  the  cotton  seed  which  is  not 
'  valuable  as  a  fertilizer.    Even  the  hull,  the  most  valueless, 


324 


FERTILIZERS  AND  NATURAL  MANURES. 


will,  in  its  turn,  become  decomposed;  and  according  to 
analysis  of  Prof.  White,  appropriate  small  amounts  of  nitro- 
gen, phosphoric  acid,  and  potash;  while  the  more  insoluble 
part  will  form  humus  to  absorb  water  and  ammonia  for  the 
benefit  of  plants,  and  by  slow  combustion  furnish  carbonic 
acid  as  a  solvent  to  prepare  mineral  food  for  them.  The 
hull,  however,  has  been  greatly  overrated,  and  would  not 
be  worth  anything  as  a  commercial  fertilizer.  On  the  farm 
it  might  be  well  appropriated  in  the  compost  heaps  above 
mentioned. 

Great  loss  of  ammonia,  as  well  as  of  the  soluble  mineral 
salts,  results  from  the  common  mode  of  rotting  cotton  seed 
for  manure.  This  is  accomplished  both  by  evaporation 
and  leaching.  Our  opinion  is  that  when  left  to  form  a  black, 
rotten  mass,  as  is  frequently  done,  at  least  three-fourths  of 
its  value  is  lost.  The  stench  that  rises  from  these  heaps 
is  surcharged  with  the  three  most  p]*ecious  substances  to 
the  farmer :  nitrogen,  phosphorus,  and  sulphur. 

285.  Experiments  with  Cotton  Seed. 

By  way  of  testing  the  comparative  value  of  cotton  seed 
rotted  in  heaps,  and  that  in  which  the  germ  was  recently 
killed,  we  instituted  the  following  experiment  in  1867. 
We  applied  at  the  rate  of  432  lbs.  of  rotten  cotton  seed  to 
the  acre,  and  by  its  side  the  same  amount  of  freshly  bruised 
seed.  The  result  in  seed  cotton,  of  the  first,  was  341  lbs. 
of  the  second,  448  lbs.    The  land  was  very  poor. 

In  1873  we  applied  at  the  rate  of  30  bushels  to  the 
acre  with  100  pounds  of  superphosphate  with  the  seed  when 
planted.  On  one  plat  the  seed  was  killed  by  boiling  water, 
and  applied  before  fermentation  could  take  place  ;  result 
915  pounds.  On  the  other,  the  seed  was  applied  green,  and 
covered  deep  in  turning  plough  furrows  so  the  nitrogen 
could  not  escape.  Result,  885  pounds  per  acre,  equal  to 
103  per  cent,  on  production,  while  the  other  produced  110 


WOOD  ASHES. 


325 


per  cent. ;  the  natural  soil  made  at  the  rate  of  435  pounds 
per  acre.  Allowing  20  cents  per  bushel  for  the  cotton  seed, 
and  paying  for  the  superphosphate,  the  net  profit  per  acre, 
at  13  cents  per  pound  for  the  cotton,  was  $12.30  cents. 
Well  rotted  cotton  seed  could  not  have  produced  such  re- 
sults. Doubtless  the  superphosphate  added  much  to  its 
value. 

The  present  year  we  instituted  an  experiment  in  which 
14  pounds  of  cotton  seed  killed,  and  an  equal  quantity 
green,  was  applied,  each  to  a  row  seventy  yards  long.  To 
an  equal  amount  of  each  on  two  other  rows  were  added  at 
the  rate  of  200  pounds  per  acre,  of  superphosphate.  The  dif- 
ference in  the  growth  and  fruiting,  (cotton  not  yet  picked) 
is  remarkable,  being  greatly  in  favor  of  the  phosphated 
rows.  This  shows  very  clearly  that  cotton  seed,  as  a  na- 
tural fertilizer,  is  very  deficient  in  phosphoric  acid. 


286.   Wood  Ashes, 

Although  not  properly  belonging  to  natural  manures, 
yet  in  a  very  just  sense  ashes  maybe  classed  with  them  ;  as 
wood  from  which  they  are  made  grows  on  the  farm,  and  is 
generally  produced  as  the  result  of  combustion,  for  home 
uses. 

As  oak  and  pine  ashes  are  by  far  the  most  comimon,  we 
give  an  analysis  of  these  two  kinds  separately;  from  which 
their  actual  relative  value  may  be  obtained : 

^f'^l,-  Potash.  Soda,  ^t?^^'  Lime.  T-^/-  ^nlP^-  ^Wor-  Sili- 
of  asn.  sia.  Acid.  Acid.    me.  ca. 

Oak  wood  10.0. . .  3.6. .  .4.8. .  .73.5. .  .5.5. .  .1.4. .  .0.2. .  -1.1 

Red  pine. . .  .0.25. . .  5.2, .  .26.8. .  .6.2. .  .47.9. .  .5.1. .  .3.0. .  .4.0. .  .2.0 

The  good  efiect  of  wood  ashes  on  most  soils  in  the  pro- 
duction of  crops,  is  too  well  known  to  be  stated  here.  In 
new  grounds  where  log  heaps  have  been  burned,  the  good 
results  last  for  years,  both  on  cotton  and  the  cereals;  only 


326 


FERTILIZERS  AKD  NATURAL  MANURES. 


the  ground  is  often  killed  for  the  first  year's  production, 
by  the  effect  of  the  fire,  or  the  overplus  of  ashes  left. 

There  are  two  objections  to  ashes  as  a  fertilizer  ;  one, 
that  most  of  the  salts  exist  in  insoluble  combinations,  hav- 
ing been  displaced  from  their  normal  condition  when  in  the 
plant  by  the  fire;  another,  that  no  ammoniacal  salt  can  be 
mixed  with  them,  without  producing  an  escape  of  the  am- 
monia. 

In  order  to  obviate  both  of  these  objections,  we  treated 
ashes  with  sulphuric  acid,  changing  all  of  the  salts  into 
sulphates.  In  1873,  at  the  rate  of  200  pounds  per  acre  of 
these  sulphated  ashes,  802  pounds  of  seed  cotton  were  pro- 
duced, while  the  simple  wood  ashes  (200  pounds)  made  675  : 
the  natural  soil  producing  607  pounds. 

The  present  year  (1874),  we  tested  ammonia  mixed 
with  them,  which  promises  well ;  although  there  was  a 
sensible  escape  of  the  ammonia,  owing  doubtless  to  the 
fact  that  the  ashes  were  not  completely  sulphated. 


CHAPTER  YIIL 

GREEN    MANURES.          VALUE    OF    MINERAL    SUBSTANCES  IN 

PLANTS.  ABSORPTION    OF    NITROGEN.  ROTATION  IN 

CROPS.  SUMMARY  OF  EXPERIMENTS  FOR  1873. 

287.   Green  Manures, 

Another  source  of  nitrogen,  but  little  thought  of  in 
this  country,  is  that  contained  in  green  or  dry  crops.  All 
weeds  and  grasses  contain  a  small  percentage  of  nitrogen, 
and  add  to  its  richness  when  ploughed  in  before  decompo- 
sition takes  place.  When  buried  in  the  soil,  a  slow  com- 
bustion takes  place,  by  which  the  nitrogen  is  converted 
into  ammonia  or  nitric  acid,  and  held  in  the  soil  for  the 
use  of  plants. 


GREEN  MANURES. 


327 


Corn  stalks,  and  Avheat  and  oat  straw  have  from  ^  to  ^ 
per  cent,  of  nitrogen,  while  that  of  beans  and  peas  has 
from  ^  to  If  per  cent,  of  this  valuable  element.  From 
this  cause,  the  pea-vine  is  recognized  as  an  important 
crop  for  green  manuring.  It  contains  also  about  ^  P^i' 
cent,  of  jDhosphoric  acid,  of  potash,  with  all  the  other 
substances  requisite  for  plant  food.  It  feeds  largely  upon 
the  atmosphere,  and  we  doubt  not  would  pay  well  to  turn 
in  as  a  green  crop,  just  as  it  gets  in  full  bloom. 

The  growth  of  any  kind  of  vegetation,  even  the  lowest 
order  of  plants,  when  turned  in  to  rot  in  the  soil,  furnishes 
more  or  less  food  for  crops.  Those  containing*  albumin- 
oids are  much  the  most  valuable,  on  account  of  the  nitro- 
gen existing  in  them.  And  they  are  generally  estimated 
according  to  the  per  cent,  of  albuminoids  found  in  them. 

In  the  autumn  of  1873,  we  gathered  400  pounds  of 
green  weeds,  a  mixture  of  several  kinds  growing  about  the 
yard.  We  took  half  of  them,  and  put  in  a  bed  for  cotton 
(row  70  yards  long),  covering  well  in  the  soil.  The  other 
half  (200  pounds)  we  burned  to  ashes,  and  put  in  another 
row  by  the  side  of  the  other.  The  ensuing  spring  planted 
with  cotton  seed.  The  cotton  not  yet  picked,  but  the  indi- 
cations are  from  the  size  of  tlie  plants,  and  the  fruiting, 
that  the  row  with  green  weeds  will  nearly  double  the  other 
in  production. 

288.   Value  of  Mineral  Substances  in  Organic  Matter. 

There  are,  in  all  plants  more  or  less  of  the  mineral 
substances  Avhich  in  their  decay,  are  in  a  fit  condition  to 
be  taken  up  by  the  succeeding  crop,  so  that  where  a 
good  crop  of  grass  and  weeds  or  pea-vines  have  decayed 
in  a  soil,  there  is  enough  of  mineral  substances  in  a  soluble 
condition  in  their  remains  to  make  a  fair  crop  of  any  of 
the  farm  products.  The  following  table  will  serve  to 
show  this  fact  in  a  clear  light. 


328 


FERTILIZERS  AND  NATURAL  MANURES. 


Table  showing  the  amount  of  each  mineral  constituent 
in  1,000  grains  of  certain  agricultural  plants  and  parts  of 
plants,  air-dried. 


In  1,000  grjiiiis, 

Cereals. 

Legnmes. 

V/OlLOn. 

Grass. 

4here  is  of 

Grain. 

straw. 

Grain. 

Straw. 

Stalk. 

Seed. 

Fibre. 

Ash  

.20.0  . 

.45.0.. 25.0. 

.50.0. 

.25.0  . 

.39.0  . 

.28.0  . 

.66.0 

Potash  

.  4.6  . 

.  6.0. 

.  9.8. 

.18.9. 

.  2.8  . 

.13.0  . 

.  7.2  . 

.17.1 

Soda  

.  0.5  . 

.  2.5. 

.  1.0. 

.  2.6. 

.  3.3  . 

.  4.0  . 

.  4.9  . 

.  4.7 

Lime  

.  0.6  . 

.  3.6. 

.  1.5. 

.15.0. 

.  6.2  . 

.  1.12. 

.  1.1  . 

.  7.7 

Magnesia , . . 

.  1.9  . 

.  1.4. 

.  1.7. 

.  3.0 

.  1.1  . 

.  7.6  . 

.  5.0  . 

.  3.3 

Sulph.  acid. 

.  0.36 

.  1.4. 

.  1.3. 

.  2.0. 

.  0.41. 

.  0.89. 

.  0.24 

.  3.4 

Phos.  acid. . 

.  8.0  . 

.  2.5. 

.  8.0. 

.  3.8. 

.  2.7  . 

.10.6  . 

.  7.6  . 

.  4.1 

Chlorine. . . . 

.  0.2  . 

.  .0. 

.  0.5. 

.  4.5. 

.  0.60. 

.  0.48. 

.  0.26. 

.  5.3 

Thus  one  thousand  pounds  of  grass  decomposed  in  the 
soil  will  furnish  four  times  as  much  potash  as  will  be  re- 
quired to  make  one  thousand  pounds  of  corn  or  wheat ;  and 
half  enough  phosphoric  acid,  with  quite  an  overplus  of  all 
the  other  mineral  substances.  The  straw  of  the  cereals 
will  furnish  more  than  enough  of  every  one  of  them  except 
magnesia  and  phosphoric  acid  ;  nearly  enough  of  the  for- 
mer, and  one-fourth  enough  of  the  latter.  To  make  peas, 
there  are  enough  of  all  the  minerals  in  grass  with  quite  an 
overplus,  except  phosphoric  acid  ;  just  half  enough  of  this, 
and  double  enough  of  potash. 

Pea  vines  furnish  a  superabundance  of  potash  and  lime, 
to  make  both  corn  and  peas,  in  fact  of  every  mineral  sub- 
stance except  phosphoric  acid.  There  is  about  one-half 
enough  of  this  to  supply  the  demand.  There  is  a  sufficiency 
in  grass  to  supply  the  demand  of  cotton  seed,  except  mag- 
nesia and  phosphoric  acid;  and  so  of  the  fibre  of  cotton. 
The  stalks  of  cotton  will  also  furnish  enough  of  all  of  the 
mineral  food  except  potash,  magnesia,  and  phosphoric  acid. 
These  three  are  quite  deficient. 

Thus  allowing  that  the  stalks  of  cotton  left  in  a  field 
weigh  as  much  as  the  seed  taken  from  them,  for  every  thou- 
sand pounds  there  will  be  taken  away  eight  pounds  of  phos- 


CARBOXACEOUS  MATTERS. 


329 


phoric  acid  in  the  seed,  more  than  is  left  in  the  stalk,  ten 
pounds  of  potash,  and  six  pounds  of  magnesia.  And  when 
it  is  remembered  under  our  system  of  clean  culture,  the 
cotton  stalk  is  about  all  the  organic  matter  left,  and  the 
cattle  take  off  a  good  portion  of  this  during  the  winter,  it 
is  not  wonderful  that  our  lands  deteriorate,  our  crops  rust, 
and  purses  remain  empty. 

The  inference  is  clear  from  the  above  facts,  that  a  good 
crop  of  grass  and  weeds,  or  other  vegetable  matter  covered 
in  the  soil,  and  properly  decomposed,  will  furnish  a  suffi- 
ciency of  all  the  mineral  substances  to  make  a  good  crop 
of  corn,  cotton  or  peas,  except  phosphoric  acid.  That  a 
piece  of  land  run  in  cotton  for  a  number  of  years  will  rap- 
idly be  deprived,  not  only  of  its  nitrogen,  but  its  phos- 
phoric acid,  and  gradually  of  its  potash  and  its  magnesia. 
That  in  a  system  of  rational  agriculture,  it  is  quite  as  im- 
portant to  husband  the  organic  matter  of  the  soil,  as  it  is 
to  save  the  nitrogen  of  the  farm-yard.  That  one  of  the 
most  important  processes  for  obtaining  soluble  mineral  food 
for  plants  is  to  ful'nish  the  land  with  vegetable  matter  by  a 
proper  rotation  of  crops.  Thus  each  successive  generation 
of  plants  takes  up  from  the  soil  a  portion  heretofore  insol- 
uble, and  renders  it  soluble,  whenever  fermentation  and 
decay  transpire.  That  the  mineral  debris  of  plants  is  in 
its  very  dissolution  rendered  soluble  by  its  extreme  me- 
chanical fineness,  and  the  action  upon  it  of  the  ammonia 
and  carbonic  acid  escaping  from  its  albuminoids  during 
the  process  of  decay,  either  by  eremacausis  or  putrefaction. 

289.  Absorption  and  Oxidation  of  JS'itrogen  hy 
Carbonaceous  Matters, 

Deherain  has  demonstrated  that  carbonaceous  matters, 
I  as  glucose,  decayed  wood,  etc.,  mixed  with  alkalies,  will 
^  absorb  nitrogen  from  the  atmosphere.    He  concludes  that 
the  nitrogen  can  at  the  temperature  of  the  soil  fix  itself  on 


330 


FEETILIZERS  AND  NATURAL  MANURES. 


carbonaceous  matters,  similar  to  decomposed  vegetation, 
as  humus  ;  but  that  the  presence  of  oxygen  is  unfavorable 
to  this  absorption.  The  clear  inference  is  that  organic  mat- 
ters in  fertilizers  and  soils  are  advantageous  to  them,  since 
when  decomposed  they  liberate  hydrogen,  which  appropri- 
ates a  part  of  the  oxygen  in  the  formation  of  water,  and 
thus  renders  the  condition  for  absorbing  nitrogen  more 
favorable  by  removing  the  oxygen  from  the  air  confined  in 
the  soil. 

He  farther  attempts  to  prove  that  the  free  nitrogen  of 
the  atmosphere  is  brought  into  combination  during  the 
oxidation  of  organic  matter  in  the  soil.  To  demonstrate 
this  he  dissolves  glucose  in  a  weak  solution  of  ammonia  in 
water,  in  a  large  flask  filled  with  a  mixture  of  equal  parts 
of  nitrogen  and  oxygen.  He  heats  the  mixture  gently 
after  closing  the  flask,  for  one  hundred  hours,  when  it  is 
found  that  the  whole  of  the  oxygen  has  disappeared,  and 
5.9  per  cent,  of  the  nitrogen.  The  same  process  with  pot- 
ash and  humic  acid  shows  a  loss  of  7.2  of  nitrogen.  These 
experiments  certainly  throw  much  light  on  the  hitherto 
obscure  subject  of  nitrification. 

Fermentation  and  putrefaction  being  reducing  pro- 
cesses, the  nitrogen  of  organic  matters  seems  to  be  inca- 
pable of  oxidation  while  they  are  at  work.  (Johnson).  The 
carbo-hydrates  or  humus  undergoing  slow  decay,  favor 
the  oxidation  of  nitrogen  when  they  come  in  contact  with 
it.  Where  a  substance  contains  much  nitrogen,  rapid  de- 
composition always  takes  place,  and  oxidation  is  arrested. 

290.  Rotation  of  Crops. 

The  old  idea  that  a  rotation  of  crops  is  useful  in  the 
fact  that  one  plant,  wheat,  for  instance,  will  need  one  kind 
of  food,  and  another  plant  a  different  kind,  and  thus  leave 
available  food  for  each  other,  does  not  apply  with  much 
force  as  regards  nitrogen,  phosphoric  acid,  and  potash. 


ROTATION  OF  CROPS. 


331 


While  it  is  easily  susceptible  of  proof,  that  all  the  consti- 
tuents except  the  three  above  mentioned,  are  found  readily- 
available  in  most  (even  in  worn)  soils,  it  is  a  remarkable 
fact,  that  all  of  the  field  crops  of  the  South  take  up  these 
important  substances  in  nearly  equal  quantities,  compara- 
tively speaking.  Thus,  while  the  cotton  crop  appropriates 
much  more  nitrogen  than  the  corn  crop,  it  takes  quite  as 
much  more  potash  and  phosphoric  acid.  This  may  be 
stated  better  thus:  There  is  taken  up  by 

One  crop  of  cotton,  31.00  Nitrogen.  9.60  Phosphoric  acid.  11.06  Potash. 
Four  crops  of  corn,  36.00      "       10.08  "  8.58 

Thus  it  is  seen  that  cotton  and  corn  feed  alike  on  these 
substances,  the  main  difference  being  as  to  the  quantity  of 
each.  A  double  crop  of  corn  would  consume  about  as  much 
of  each  of  these  substances  as  a  half  crop  of  cotton.  Then 
these  two  crops  will  exhaust  of  the  three  most  important 
principles  of  crop  food  about  in  the  same  ratio.  The  other 
three  crops  vary  but  little  as  to  the  mineral  elements,  the 
oats  destroying  more  potash  in  proportion  than  the  others, 
and  the  peas  less  phosphoric  acid.  Each  of  them  consumes 
more  nitrogen  than  corn  and  wheat. 

It  is  no  doubt  true,  that  a  soil  may  be  exhausted  of 
certain  substances  so  as  to  produce  one  crop  better  than 
another.  But  this  depends  more,  oftentimes,  on  the  pre- 
vious cultivation  and  physical  condition  of  the  soil  than 
its  exhaustion.  Thus,  wheat  sown  in  stubble  wdll  not  pro- 
duce near  as  much  as  w4ien  sowed  after  cultivated  crops. 
Cotton  will  do  better  in  stubble  than  in  other  lands,  all 
other  things  being  equal. 

At  one  time  it  was  supposed  that  each  plant  left  behind 
a  different  kind  of  excrement  in  the  soil,  which,  while  in- 
jurious to  itself  would  benefit  others.  There  is  not  the 
least  evidence  that  any  such  excreta  are  left  in  the  soil, 
much  less  that  they  act  in  the  manner  aboA^e  stated.  The 


332 


FERTILIZERS  AND  NATURAL  MANURES. 


more  rational  theory,  now  generally  received,  that  this 
preference  of  crops  to  succeed  each  other,  depends  on  the 
exhaustion  of  certain  mineral  substances  by  one  plant  not 
so  much  needed  by  another,  can  account  only  in  part  for 
the  fact  under  consideration. 

But  there  are  injuries  done  to  the  physical  qualities  of 
soils  by  lack  of  a  proper  rotation  of  crops,  which  are  so 
hurtful  as  to  demand  change,  even  in  the  presence  of  an 
abundant  supply  of  fertilizing  agents.  Thus,  land  con- 
tinued too  long  in  clover,  becomes  what  has  been  aptly 
termed  clover  sick;  so  that  it  will  not  produce  clover  or 
anything  else,  well.  This  is  doubtless  owing  to  an  accu- 
mulation of  vegetable  matter  in  an  undecomposed  and  fer- 
menting state.  Acids  are  generated,  the  soil  sours,  and 
vegetation  sickens  and  fails  "to  reward  the  tiller's  toil." 

Just  the  opposite  result  is  produced  by  running  land 
for  a  series  of  years  in  cotton — the  vegetable  matter  of  the 
soil  is  destroyed,  and  its  stores  of  nitrogen  dissipated,  the 
land  becomes  more  impacted,  and  less  friable,  hard  and 
cloddy  and  thirsty,  and  the  application  of  nitrogen  and 
phosphoric  acid  artificially,  no  longer  produces  remunera- 
tive crops. 

Wheat  fails  much  more  rapidly  after  wheat,  than  any 
of  the  crops  mentioned,  demanding  an  immediate  rotation. 
We  suppose  this  is  owing  to  two  causes  :  1st,  the  lack  of 
aeration,  resulting  from  ploughing  and  opening  the  pores 
of  the  soil  to  the  air ;  and  2d,  the  fact  that  wheat  is  a 
\ic2ite  feeder,  and  one  crop  in  our  thin  soils  so  reduces  the 
soluble  wheat  food,  that  even  a  second  crop  cannot  be 
grown  without  an  intervening  crop  of  some  kind.  Oats 
differ  essentially  from  wheat  in  this  respect,  as  they  will 
grow  two  and  even  three  crops  sometimes  from  volu72teer 
seed,  as  it  is  called. 

Another  peculiarity  of  wheat,  not  exactly  accounted 
for,  is  the  good  effect  which  change  of  seed  has  upon  the 


PLANTS  DIFFERENTLY  CONSTITUTED. 


333 


crop.  Sowing  the  same  variety  a  number  of  years  on  the 
same  soil,  or  in  the  same  neighborhood,  even  with  a  rota- 
tion of  crops,  will  cause  the  seed  to  depreciate  and  not 
produce  as  much  as  other  seed  of  the  same  variety  trans- 
planted from  a  distance  ;  especially  from  a  more  northern 
latitude.  This  may  possibly  be  owing  to  the  fact  of  climate 
as  well  as  soil,  and  seems  to  demand  a  rotation  of  seeds ^  as 
well  as  of  soil. 

It  is  easy  to  perceive  then,  that  a  soil  which  has  been 
drawn  upon  largely  for  one  particular  constituent  essential 
to  plant  life,  will  ultimately  become  robbed  of  that  consti- 
tuent in  any  available  form,  or  so  reduced  as  not  to  pro- 
duce remunerative  crops.  The  abandoned  lands  of  the 
cotton  belt,  thrown  out  because  too  poor  to  pay  for  cul- 
ture, are  a  standing  evidence  of  this  fact.  And  yet  the  old 
idea  of  estimating  such  a  rotation  by  the  deficiency  of  any 
ingredients  than  the  most  important,  as  nitrogen,  phos- 
phoric acid,  and  potash,  is  to  our  mind  illogical. 

291.  Plants  Differently  Constituted, 

Plants,  like  animals,  are  differently  constituted  ;  some 
being  much  less  thrifty  under  untoward  circumstances 
than  others.  The  turnip  belongs  to  the  helpless  class. 
Having  very  short  roots,  it  cannot  flourish  in  a  poor  soil 
w^here  nutriment  is  sparse  and  scattered,  but  requires  con- 
centrated food  near  by.  Thus,  a  little  phosphoric  acid 
will  give  it  a  vigorous  start,  and  cause  a  greatly  increased 
production  from  a  small  outlay. 

There  are  other  plants  which  may  be  termed  industrious. 
They  seem  not  to  require  such  delicately  prepared  food, 

'  •  and  will  live  and  flourish  in  soils  where  feebler  plants  wilt 
and  die.    They  are  termed  coarse  feeders.    The  clovers  and 

j   some  of  the  grasses  are  good  representatives  of  this  class. 
They  send  out  their  roots  to  great  distances  and  depths  in 

•  quest  of  food,  and  eliminate  it  in  their  structures,  rendering 


334 


FERTILIZERS  AND  NATURAL  MANURES. 


it  available  for  the  less  vigorous  and  more  delicate  crops 
in  the  laboratories  of  nature,  so  much  better  than  those  of 
art. 

Among  this  class  of  plants  the  sainfoin  is  highly  es- 
teemed in  Europe;  growing  luxuriously  in  thin,  porous 
limestoue  soils,  where  others  are  feeble  and  unproductive, 
it  wrests  from  the  rocks  the  semi-soluble  substances  which 
are  so  scattered  and  unavailable  to  most  others,  and  by  the 
decay  of  several  successive  crops,  it  enriches  the  surface 
soil,  and  prepares  it  for  the  subsistence  of  the  more  delicate 
plants.  In  our  climate,  the  corn-field  pea  is  perhaps  the 
best  of  all  others  for  this  rotation.  The  Bermuda  grass 
would  be  excellent,  especially  for  hill-sides,  but  for  its  being 
such  a  pest  to  our  crops;  and  when  once  seated,  so  difficult 
to  extirpate. 

292.  Benefit  of  Resting  Lands, 

Land  is  made  better  by  lying  fallow  from  several  causes. 
The  organic  matter  of  the  soil  is  increased,  which  not  only 
improves  it  physically,  by  rendering  it  more  friable,  mak- 
ing it  hold  more  hygroscopic  water  and  ammonia,  by  the 
absorbing  power  of  humus,  but  chemically  also,  in  several 
important  particulars.  Stores  of  organic  nitrogen  are  held 
in  this  vegetable  matter,  to  be  converted  into  ammonia 
and  nitric  acid  when  decay  takes  place.  Carbonic  acid  is 
constantly  forming,  and  mingling  with  the  moving  capil- 
lary water  of  the  soil,  which,  as  it  passes  downward  by 
gravitation,  and  upward  by  capillary  force,  acts  as  a  sol- 
vent upon  the  insoluble  phosphates,  and  other  less  valuable 
substances. 

The  mineral  debris  of  this  vegetable  matter,  also  fur- 
nishes available  phosphoric  acid,  potash,  magnesia,  and  all 
of  the  mineral  constituents  of  plants,  as  soon  as  it  under- 
goes decomposition.  The  tap  roots  of  plants  bring  up 
these  substances  in  some  instances,  for  several  feet  below 


BEXEFIT  OF  RESTIXG  LAXDS. 


335 


the  surface,  and  deposit  tliem  within  the  reach  of  the  sur- 
face roots ;  which  themselves  in  their  turn  decay  and  help 
to  improve  the  soil. 

Further,  there  is  constantly  going  on  through  the  agen- 
cies of  nature,  as  wind,  rain,  and  frost,  and  the  chemical 
action  of  the  oxygen  and  carbonic  acid  of  the  atmosphere, 
a  process  of  weathering^  as  it  is  termed,  which  renders  a 
greater  or  less  amount  of  plant  food  soluble  each  year.  It 
is  this  soluble  food  that  makes  the  crops.  Each  crop  carries 
ofi'  more  than  is  formed,  annually.  Each  year  of  rest,  what- 
ever is  formed  is  saved,  and  the  land  by  that  much  im- 
proved. 

But  the  greatest  benefit  to  land  from  resting  is,  we  are 
satisfied,  the  increased  amount  of  available  nitrogen  pro- 
duced by  it  in  the  soil.  The  cultivation  of  land  unques- 
tionably diminishes  this  element,  not  only  by  what  is  ap- 
propriated to  the  plant,  and  carried  oflf  in  the  seed,  but  also 
by  evaporation  and  leaching,  after  it  has  assumed  the  form 
of  ammonia  and  nitric  acid.  Ammonia  is  held  to  a  large 
extent  by  hygroscopic  water  in  the  soil.  The  more  the 
land  is  stirred  by  the  plough,  the  more  this  water  escapes, 
and  with  it  a  certain  amount  of  ammonia,  however  minute. 
In  the  same  way,  the  more  pulverulent  the  soil  is  made  by 
the  plough,  the  more  readily  and  rapidly  rain  water  escapes 
to  the  subsoil,  carrying  with  it  the  soluble  nitrates,  and  by 
thus  far  impoverishing  the  land.  As  long  as  the  soil  is  at 
rest,  then,  there  is  a  gradual  increase  of  nitrogenous  matters. 

This  quiescent  state  is  favorable  to  the  absorption  of 
ammonia,  by  oxide  of  iron,  alumina,  and  humus;  all  of  which 
have  the  power  of  absorbing  and  fixing  ammonia  from  the 
air.  Likewise  all  that  is  brought  down  by  rains  is  absorbed 
and  held  by  the  soil,  with  much  more  tenacity,  where 
the  land  is  left  to  itself.  Its  very  compactness  protects  it 
from  the  evaporating  influence  of  the  winds,  and  the  burn- 
ing sun.     Particularly  in  southern  climates  is  this  rest 


336 


FERTILIZERS  AND  NATURAL  MANURES. 


needed,  because  here  the  causes  which  produce  volatiliza- 
tion, are  much  more  prevalent  than  in  cold  countries. 

Besides,  they  have  their  long  freezing  winters,  and 
the  covering  of  their  heavy  snows,  which  hold  in  store 
the  nitrogen  for  the  summer  crops;  while  our  hot  sun, 
bald  lands,  and  heavy  rains,  make  our  soils  poor  in  this 
important  element.  A  good  coating  of  grass  and  weeds, 
while  it  prevents  evaporation,  favors  the  retention  of  am- 
monia. In  this  way,  grain  crops  are  much  less  exhaustive 
of  this  substance,  than  cultivated  crops  (especially  cotton); 
and  this  furnishes  another  important  reason  for  the  resting 
of  lands  at  the  South. 

293.  Best  Rotation  in  Cotton  Culture, 

As  regards  the  field  crops  of  the  South,  experience 
teaches,  that  a  field  run  in  cotton  for  a  number  of  years 
will  exhaust  the  land,  not  only  so  as  to  produce  but  little 
cotton,  but  equally  as  little  corn,  or  wheat,  or  oats.  An 
intervening  crop,  however,  of  either  will  help  the  land  for 
cotton  a  succeeding  year ;  resting  without  a  crop  will  do 
even  better,  and  two  years'  rest  much  better  than  one. 

To  our  mind,  the  benefit  of  this  rotation  is  very  clear. 
The  organic  matter  has  been  lessened  every  year  in  the  soil 
by  the  clean  culture  of  cotton,  and  the  nitrogen  has  been 
exhausted  in  the  same  proportion.  A  wheat  or  oat  crop,  or 
a  year's  rest,  to  grow  up  in  grass  and  weeds,  will  increase 
the  vegetable  matter,  and  by  consequence,  the  nitrogen. 
The  mineral  debris  of  this  organic  matter  will,  to  the  extent 
of  its  decomposition,  supply  all  the  mineral  elements  in 
available  forms,  especially  that  most  needed,  phosphoric 
acid. 

Rotation  of  crops  must  be  regulated,  then,  by  climate, 
soil,  and  production.  What  would  be  a  good  rotation  in 
Virginia,  or  any  wheat  country,  would  utterly  fail  with  us. 
What  would  apply  to  lime  lands  would  not  suit  aluminous 
or  sandy  lands. 


SUMMARY  OF  EXPEIliMENTS  FOR  1873. 


337 


What  the  farmer  wants  is  a  paying  rotation.  He  can- 
not afford  to  adopt  one  which  will  improve  his  land  at  the 
expense  of  his  purse.  That  rotation  of  crops  which  will 
keep  his  lands  in  good  heart  and  bring  him  in  the  most 
money,  is  the  one  that  every  sensible  farmer  needs — espe- 
cially under  our  present  impoverished  condition.  As  a 
general  rule,  two  crops  of  cotton  may  be  run  on  land 
having  a  supply  of  vegetable  matter,  with  about  as  good 
results  the  second  as  the  first  year.  It  would  be  even  bet- 
ter than  an  intervening  crop.  Then  corn  to  succeed  the 
cotton,  on  the  levellest  and  most  productive  portions,  and 
wheat  and  oats  on  the  rolling  lands.  The  fourth  year, 
rest. 

In  a  four  years'  rotation  of  crops,  where  lands  are  in 
good  heart  and  fertilizers  used,  this  is  not  requisite.  But 
most  of  our  worn  soils  should  lie  fallow  every  fourth  year 
at  least.  ,  The  best  practical  farmers  at  the  South  have 
long  since  adopted  this  pLan,  with  the  very  best  results. 
The  Hebrew  rotation  has  six  years  of  cultivation,  one  of 
rest.  This  was  the  direct  command  of  Infinite  wisdom, 
long  before  science  had  shown  its  necessity  as  a  means  of 
recuperating  worn  soils. 

294.   Deductions  from  Experiments, 

We  sum  up  the  practical  bearings  of  experiments,  made 
at  Athens,  Ga.,  in  1873,  as  follows  : 

1.  That  there  is  a  great  waste  of  ammonia  when  Peru- 
vian guano  is  used  in  its  concentrated  form  ;  it  should  be 
mixed  with  superphosphate,  alkaline  salts,  etc. 

2.  That  no  combination  of  salts,  leaving  out  soluble 
phosphoric  acid,  will  pay  on  our  worn  soils. 

3.  That  taken  separately,  none  of  the  salts  sold  as  fer- 
tilizers to  make  home  compounds,  will  pay.  Their  virtues, 
if  any,  must  be  in  chemical  action  upon  each  other,  and 
the  substances  with  which  they  are  composted. 

15 


338 


FERTILIZERS  AND  NATURAL  MANURES. 


4.  That  ashes  treated  with  sulphuric  acid  will  greatly 
improve  their  fertilizing  qualities. 

5.  That  200  lbs.  of  a  good  ammoniated  superphos- 
phate is  about  the  quantity  to  be  used  on  an  acre  of  cotton. 

6.  That  a  soil  abounding  in  vegetable  matter  will  pay 
a  much  better  per  cent,  with  commercial  fertilizers  than 
one  having  but  little  of  this  substance. 

7.  That  a  large  amount  of  fertilizers  (say  half  a  ton 
per  acre)  will  not  pay  with  low  priced  cotton. 

8.  That  with  good  cultivation,  good  fertilizers  will 
pay,  even  at  the  lowest  rates  of  cotton ;  but  with  bad  cul- 
tivation, they  will  hardly  pay  at  any  price. 

9.  That  while  potash  is  more  indispensable  to  plant 
life  than  soda,  the  latter  may  partially  replace  the  former 
under  certain  circumstances. 

10.  That  the  di-phosphate  of  lime,  being  less  soluble 
in  cold  water,  is  not  so  efficient  as  the  bi-phosphate  as  a 
fertilizer. 

11.  That  stable  manure,  either  fresh  or  rotted,  applied 
with  a  high-graded  superphosphate,  makes  a  very  efficient 
fertilizer  for  cotton. 

12.  That  cotton  seed  applied  with  the  germ  killed  (or 
green,  if  put  in  deep),  in  conjunction  with  a  good  super- 
phosphate, makes  a  good  fertilizer. 

13.  That  lime  should  never  be  used  in  conjunction 
w^ith  a  superphosphate;  and  the  application  of  super- 
phosphates to  calcareous  soils  is  of  doubtful  utility. 

14.  Fertilizers  applied  during  the  growth  of  the  crop, 
to  keep  up  a  supply  of  nutrition  to  the  rootlets,  will  not 
pay  under  ordinary  circumstances. 

15.  That  ammonia  is  the  most  active  and  efficient 
form  of  nitrogen,  when  applied  as  a  fertilizer;  and  that 
organic  nitrogen  in  certain  albuminoids  is  more  effectual 
than  the  nitrates. 

16.  That  the  value  of  nitrogen  and  phosphoric  acid  to 


SUMMARY  OF  EXPERIMENTS  FOR  1873. 


339 


a  farmer,  depends  on  their  forms  and  combinations,  not 
their  commercial  value — which  is  rated  according  to  the 
law  of  supply  and  demand. 

17.  That  the  application  of  soluble  manures  in  a  liquid 
form,  is  better  and  more  efficient  than  when  applied  in  the 
dry  state. 

18.  That  lime  will  pay  on  soils  abounding  in  organic 
matter ;  on  other  soils  its  application  is  of  doubtful  utility. 

19.  That  subsoils  do  not  germinate  seeds  or  grow 
plants  like  surface  soils. 

20.  That  early  planting  of  cotton  will  not  produce  as 
much  as  that  planted  later,  when  the  ground  becomes 
warm  and  the  plant  is  not  retarded,  but  grows  off  vigor- 
ously and  healthy. 

21.  That  subsoiling  cotton  lands  will  jDay  for  the  extra 
labor  on  our  clay  soils. 

22.  That  one  stalk  in  the  hill  will  produce  more  cotton 
than  two  or  more  stalks. 

23.  That  topping  cotton  is  rather  a  detriment  than  an 
advantage  to  the  crop. 

24.  That  cotton  planted  in  narrow  rows,  2-|  feet  wide, 
and  fertilized  on  thin  land,  will  produce  more  fruit  than 
in  w4der  rows,  of  a  seasonable  year. 

25.  That  the  difference  between  a  rich  and  poor  soil  is 
probably  owing  to  the  amount  of  available  nitrogen  and 
phosphoric  acid,  held  in  soluble  conditions  with  the 
humus  or  black  matter  resulting  from  the  decay  of  plants, 
in  which  there  is  always  a  sufficiency  of  the  other  mineral 
elements. 

26.  That  subsoiling  land  for  corn,  will  pay  for  the 
extra  labor,  even  of  a  seasonable  year,  much  better  of  a 
dry  year. 

27.  That  deep  ploughing  of  corn  during  some  seasons, 
at  least  on  clay  land,  seems  to  answer  as  well,  if  not  better, 
than  shallow  culture. 


340  FERTILIZERS  AND  NATURAL  MANURES. 

28.  That  five  by  three  feet  is  the  best  distance  to  plant 
corn  on  medium  land  of  a  seasonable  year. 

29.  That  pulling  fodder  does  not  seriously  injure  the 
corn  after  it  passes  the  milk  stage. 

30.  That  superphosphate  is  the  best  fertilizer  for  legu- 
minous plants — not  because  it  is  a  preferred  food,  but 
because  available  phosphoric  acid  is  deficient  in  our  soils. 

31.  That  large  crops  of  turnips  can  be  made  on  thin 
lands,  by  the  application  of  superphosphate  of  lime ;  and 
inferentially,  sheep  husbandry  might  be  made  profitable  by 
feeding  on  turnips  and  fertilizing  the  soil,  as  well  as  for 
the  wool  and  mutton,  and  the  consequent  reduction  of  the 
amount  of  cotton  by  the  division  of  labor. 


PAET  VIII. 
ANIMAL  NUTRITION. 


CHAPTER  1. 

CATTLE  FOODS. — LAAYS  WHICH  GOVERN  FLESH 
BUILDING,  ETC. 

295.  JEJxperime7its  in  Germany, 

Animal  Nutrition  is  noAV  a  subject  of  great  interest 
among  scientific  agriculturists,  involving  the  physiology  of 
domestic  animals,  as  horses,  cattle,  sheep  and  hogs,  and  the 
most  economical  kinds  and  amounts  of  food,  for  the  maxi- 
mum production  of  muscle  for  labor,  and  meat,  milk,  but- 
ter, etc.,  for  food.  This  of  course  demands  much  more 
attention  in  Europe  than  here,  as  the  means  for  animal 
and  vegetable  production  are  much  less  plentiful. 

Feeding  experiments  have  been  instituted  at  different 
experimental  stations  in  England  and  Germany,  throwing 
much  light  upon  this  intricate  subject. 

We  are  indebted  to  Prof.  Atwater,  of  Middletown, 
Connecticut,  for  a  condensed  statement  of  experiments 
and  results  made  since  1866,  at  the  stations  of  Moeckern, 
by  Kuehn,  and  at  Hohenhiem,  by  Wolff  and  Fleischer,  on 
the  feeding  of  cows,  and  the  production  of  milk. 

296.  Proximate  Composition  of  Animal  Substances, 

In  animals  the  organic  principles  exist  in  about  the 
following  proportions: 


342 


ANIMAL  NUTRITION. 


Water  74  percent. 

Gelantine  10   "  " 

Fat  7   "  " 

Albumen  8  " 

Fibrin  1    "  " 

This  is  supposed  to  refer  to  animals  in  good  condition. 
The  fr.t  is  very  variable  in  all  animals,  and  so  are  some  of 
the  other  principles.  This  may  serve  as  an  approxima- 
tion. 

The  mineral  matters  in  animals,  as  to  the  whole  system, 
would  be  about  as  follows: 

Phosphate  of  lime  4.50 

Carbonate  of  lime  0.50 

Alkaline  and  other  salts.  75 

Althouuh  water  constitutes  three-fourtlis  of  the  struc- 
ture of  animals,  and  is  very  important  in  its  place,  vege- 
tables having  the  most  water  are  the  least  nutritious,  and 
they  are  generally  valued  in  proportion  to  the  small 
amount  of  water  in  them. 

2C  7.  Flesh- Formers  and  Fat- Formers. 

Physiologists  have  divided  the  organic  substances  of 
plants  into  water,  flesh-formers,  fat-formers,  accessories,  and 
mineral  matter.  Water,  as  you  know,  is  composed  simply 
of  hydrogen  and  oxygen  :  the  fat  formers  have  only  the 
addition  of  carbon,  while  the  flesh-formers  have  all  of  the 
organic  elements.  Food,  to  be  highly  nutritious,  must  have 
all  four  of  these  principles.  They  are  termed  nitrogenous, 
because  none  of  the  others  have  the  important  element  of 
nitrogen.  They  are'  also  termed  albuminoids,  from  albu- 
men, the  leading  principle  of  this  class. 

The  fat-formers  are  also  called  carbonaceous,  or  heat 
giving  principles.  They  have  but  little  to  do  in  building 
up  the  animal  structure,  but  may  be  considered  as  the  fuel, 
by  which  the  heat  of  the  body  is  maintained.    This  process 


FLESH-FORMERS  AND  FAT-FORMERS. 


343 


is  very  similar  to  the  burning  of  wood,  coal,  and  other 
substances.  The  oxygen  of  the  air  is  inhaled  into  the 
lungs,  meets  the  carbon  of  the  food,  which  has  been  thrown 
off  into  the  venous  blood;  combustion  takes  place,  and 
animal  heat  is  thus  produced. 

Less  of  this  carbonaceous  food  is  required  in  warm  than 
in  cold  climates.  Hence,  oily  food  is  the  principal  subsist- 
ence of  the  Greenlander  and  the  Esquimaux,  as  by  it  a 
constant  combustion  is  kept  up  in  the  system,  which  en- 
ables them  to  withstand  the  intense  cold  of  their  inhospi- 
table clime. 

The  food  of  animals  contains  carbon  in  large  quantities, 
which  being  digested,  is  carried  throughout  the  system  by 
the  lymphatic  vessels,  and  what  is  not  needed  to  build  up 
the  flesh,  is  taken  up  by  the  capillaries,  carried  into  the 
larger  veins  back  to  the  heart,  and  from  thence  to  the 
lungs,  where  it  meets  with  the  oxygen  of  the  air.  Every 
breath  we  inhale  the  oxygen  is  converted  by  a  chemical 
union  into  carbonic  acid,  and  expelled  by  the  exhaling 
breath.  The  blue  blood  of  the  veins,  w^hich  we  see  some- 
times in  thin-skinned  people,  is  colored  with  carbon. 

Most  generally,  heat  is  produced  by  the  chemical  union 
of  two  bodies.  Thus,  water  poured  upon  caustic  lime, 
produces  heat  from  its  union  with  the  lime;  so  the  imion 
of  the  carbon  of  the  blood  in  the  lungs  with  the  oxygen 
of  the  air,  in  uniting  to  form  carbonic  acid  gas  produces 
animal  heat.  Thus,  of  a  very  cold  morning,  you  can  warm 
your  hands  by  blowing  your  breath  upon  them.  This 
animal  or  blood  heat,  stands  at  98^  F.  in  a  healthy 
person. 

The  only  use  of  fat  in  the  animal  system  seems  to  be  to 
supply  carbon  for  the  production  of  heat ;  and  when  an 
excess  is  formed,  to  lay  up  in  store  for  future  use. 


344 


ANIMAL  NUTRITION. 


298.  Proportion  of  Different  Foods  Digested  hy  Animals. 

The  proportion  of  different  foods  digested  by  animals 
was  also  tested  by  a  long  series  of  experiments,  by  ac- 
curately estimating  the  amount  of  food  and  excrement, 
as  well  as  their  composition  by  analysis. 

These  experiments  were  begun  in  1868,  at  Weende, 
near  Gottingen,  by  Henneberg  and  Stohman,  and  have 
been  continued  by  a  number  of  eminent  experimenters  up 
to  the  present  time. 

A  portion  of  the  food  consumed  by  animals  is  digested, 
as  is  well  known,  and  the  remainder  passes  off  as  excre- 
ment. The  chemical  constituents  then,  of  the  food  and  of 
the  excrement  being  known,  we  can  easily  tell  the  amount 
digested,  by  subtracting  the  latter  from  the  former. 

The  following  table  is  the  mean  result  of  66  experi- 
ments with  eleven  different  oxen.  The  figures  show  the 
amount  digested  in  100  parts  of  the  different  food  ma- 
terials. 

Kind  of  food,     ^^o^a^c^  Crude  fibre.      Fat.      ^^g^^^^,  ^S!' 

Clover  hay  56  41  45  69  51 

Meadow  hay  63  63  39  63  63 

Bean  straw  50  36  55  65  50 

Oat  straw  52  59  34  44  47 

Rye  straw  53  60   ?   ?  49 

Wheat  straw  45  52  27  40  26 

From  this  table  it  appears  that  the  digestibility  of 
different  kinds  of  straw,  and  the  woody  fibre  of  fodder 
plants,  is  much  greater  than  it  has  been  heretofore  sup- 
posed to  be. 

Among  their  most  interesting  experiments,  we  find 
that  of  100  of  the  organic  substance  of  potatoes,  89  was 
digested;  of  turnips  90;  of  bean  meal  93;  of  wheat  bran 
84.8;  of  rape-oil  cake  58.8,  and  of  cotton-seed  cake  49.7. 
The  reason  so  little  of  the  latter  was  digested,  was  owing 


CAEBO-HYDEATES  AND  ALBUMINOIDS  AS  FOOD.  345 


to  the  amount  of  hulls  it  contained,  from  imperfect  decor- 
tication. 

In  100  parts  there  was  digested  in  the  experiments 
made,  of 

Crude  fibre.         Fat.  hydratek  Albuminoids 

Potatoes  94.9  64.9 

Turnips  97.7  76.8 

Bean  meal  70  99.7  94  94.6 

Wheat  bran  69.1...  .    88.2  90.8  72.5 

Rape  cakes   ?   69.8  79.6  77.9 

Cotton  seed  cak  e  . .  22 . 7  90.8  46 . 2  73 . 8 

We  should  be  particularly  interested  in  the  cotton- 
seed cake,  as  it  is  so  abundantly  produced  in  this  country. 
Its  value  as  cow  food  rates  high,  as  shown  by  these  experi- 
ments, four  in  number.  Wolff,  who  made  them,  remarks: 
''The  chief  value  of  oil  cakes  is  due  to  their  large  content 
of  albuminoid  and  fatty  substances,  and  it  is  interesting 
that  these  ingredients  in  cotton-seed  cake,  according  to 
direct  experiments,  are  scarcely  less  digestible  than  in 
other  oil  cakes." 

To  show  how  little  we  appreciate  such  things  in  this 
country,  as  compared  with  Europe,  we  are  credibly  in- 
formed that  the  Memphis  Oil  Co.  ship  from  8,000  to  10,000 
long  tons  of  this  substance  to  England  annually  at  $42 
to  $45  per  ton  delivered. 

299.  3Iixing  Carho-hydrates  and  Albuminoids  as  Food, 

Experiments  were  also  tried  in  mixing  different  foods 
with  hay  and  straw;  as  meal,  oil,  and  potatoes,  with  the 
following  results  :  1st.  The  digestion  of  the  carbo-hydrates, 
as  crude  fodder,  straw,  etc.,  are  not  materially  aided  by 
the  presence  of  nitrogenous  substances,  as  crushed  beans 
and  other  easily  digestible  substances.  2d.  When  carbo* 
hydrates,  which  are  easy  of  digestion,  as  starch,  sugar, 
potatoes,  etc.,  are  used  in  considerable  quantities  with 
15* 


346 


ANIMAL  NUTRITION. 


crude  fodder  materials,  the  effect  is  to  decrease  their 
digestion.  Thus,  in  experiments  by  Wolff  at  Hohenheim; 
sheep  fed  on  clover  hay  alone,  digested  63.7  per  cent,  of 
the  albuminoid,  and  51.2  of  the  crude  fibre.  In  mixed 
rations  of  clover  hay  and  potatoes,  the  albuminoids 
digested  were  reduced  to  45.6  per  cent,  and  the  crude  fibre 
to  43.3. 

These  experiments  teach  that  straw  is  nearly  as  diges- 
tible as  hay.  Henneberg  found  that  twenty  pounds  of 
straw  produced  as  much  digestible  substances  as  17  lbs. 
of  hay.  The  digested  material,  however,  of  the  hay,  had 
much  more  of  albuminoids,  and  much  less  non-nitrogenous 
matter,  as  fat,  carbo-hydrates  and  crude  fibre,  than  the 
straw.  This  by  itself  would  then  be  too  deficient  in 
nitrogen  to  make  a  good  food  for  cattle.  But  mixed  with 
nitrogenous  substances,  as  clover  or  oil  cakes,  the  straw 
may  be  utilized  and  made  very  profitable. 

Thus  the  amount  of  albuminoids,  carbo-hydrates,  fat, 
and  fibre  needed  by  an  animal,  may  be  given  in  mixtures 
of  different  foods  upon  the  most  economical  scale,  so  that 
none  need  be  lost. 

300.  Lavas  which  govern  Flesh  Building, 

Further  experiments  have  been  made  with  partial  suc- 
cess, to  determine  the  laws  which  govern  flesh  building. 
It  is  known  that  much  of  the  nitrogen  taken  into  the  sys- 
tem of  animals,  passes  off  with  the  urine.  It  has  been 
ascertained  that  this  comes  from  the  transformation  of  the 
flesh  of  the  animal  body,  and  that  the  amount  of  nitrogen  in 
the  urine,  indicates  with  precision  the  amount  of  the  albu- 
minoid constituents  transformed.  If,  therefore,  at  any 
time  there  is  a  comparative  deficiency  of  the  amount  of 
nitrogen  in  the  urine,  with  that  of  the  food  digested,  it  is 
very  clear  that  it  has  been  retained  in  the  body,  and  that 
more  flesh  has  thus  been  built  up,  than  has  been  consumed. 


LAWS  WHICH  GOVERN  FLESH  BUILDING. 


347 


If,  however,  there  is  found  to  be  more  nitrogen  in  the 
urine  than  is  taken  up  from  the  food,  it  is  presumptive 
evidence  that  the  animal  is  decreasing  in  flesh.  By  these 
means  the  effect  of  different  food  substances  in  flesh  build- 
ing may  be  ascertained. 

There  is  no  doubt  that  different  kinds  of  foods  affect 
materially  the  flesh  of  animals.  Some  experiments  with 
pigs  in  England  showed  that  those  nourished  with  milk 
gave  the  best  flavored  meat,  and  the  greatest  weight; 
next  to  these  were  those  fed  on  maize,  barley,  oats  and 
peas.  Oil  cakes  and  oil  seeds  produce  a  loose  fatty  flesh, 
of  an  unpleasant  taste;  beans,  hard,  indigestible  and  un- 
savory meat,  and  acorns  but  little  better  ;  while  potatoes 
give  a  loose,  light,  tasteless  flesh,  which  wastes  away  very 
much  in  cooking. 

Mr.  Lawes  of  England  makes  an  important  suggestion 
as  to  the  economy  of  feeding  animals  intended  for  the 
butcher.  He  assumes  that  there  will  be  more  fat  produced 
the  less  the  amount  of  food  expended  by  respiration. 
Hence  the  lessening  of  the  time  for  the  fattening  process 
is  an  important  item.  In  other  words,  the  most  economical 
plan  is  to  fatten  as  quickly  as  possible. 

He  experimented  with  a  pig,  and  found  that  500  pounds 
of  barley-meal  given  as  freely  as  he  could  eat,  increased  his 
weight  from  100  to  200  pounds  in  seventeen  weeks.  Had 
a  longer  period  of  time  been  taken  in  the  consumption  of 
the  food,  Mr.  Lawes  shows  very  conclusively,  that  a  good 
portion  of  it  would  have  been  expended  in  the  maintenance 
of  the  animal's  existence,  and  not  near  the  amount  of  fat 
have  been  produced. 


348 


ANIMAL  NUTRITION. 


CHAPTEE  II. 

RESPIRATION    APPARATUS. — EXPERIMENTS  ON  THE  PRODUC- 
TION   OF   MILK.  PRESERVATION    AND  CONDENSATION 

OF  MILK.  BUTTER  MAKING. 

301.  Respiration  Apparatus, 

In  order  to  determine  the  functions  of  the  constituents 
of  food,  albuminoids,  fats,  carbo-hydrates,  crude  fibre,  and 
mineral  matters  in  the  animal  economy,  various  experi- 
ments have  been  instituted,  with  a  respiration  apparatus, 
to  determine  the  products  of  transformation  through  the 
lungs  and  skin. 

Pettenhofer  invented  the  first  successful  apparatus  at 
Munich.  It  consists  of  a  large  apartment  of  air-tight  walls 
in  which  the  animal  is  placed.  A  current  of  fresh  air  is 
admitted  for  the  animal  to  breathe,  and  afterwards  con- 
ducted out  into  a  gasometer,  where  it  is  measured  and 
analyzed.  By  comparing  it  with  the  air  before  it  passed 
through  the  apparatus,  the  material  added  to  it  by  the  res- 
piration of  the  animal,  is  easily  determined.  At  the  same 
time  the  excrement  and  urine  are  preserved  and  analyzed, 
and  thus  from  these  three  important  sources,  we  learn  what 
materials  of  the  food  contribute  to  the  heat  and  muscular 
force  of  the  animal.  By  the  means  thus  employed,  we 
have  good  reason  for  hoping  that  animal  nutrition,  about 
which  there  has  been  so  much  mere  theory,  will  soon  rank 
as  an  exact  science. 

Experiments  made  upon  sheep,  with  the  respiration 
apparatus,  show  that  in  order  properly  to  economize  food, 
it  is  necessary  to  protect  animals  from  the  conditions 
which  induce  perspiration.  The  feeding  was  generally 
soon  followed  by  the  excretion  of  carbonic  acid.  The 


EXPERIMENTS  ON  THE  PRODUCTION  OF  MILK. 


349 


i  .  same  rules  vvliicli  governed  this  excretion  applied  with 
equal  force  to  the  perspiration  or  exhalation  of  water. 
Both  of  them  were  greater  or  less,  according  to  the 
amount  and  character  of  food  consumed. 

A  place  of  medium  temperature  was  found  to  be  the 

f  best  for  feeding  purposes  ;  as  a  less  heat  required  more 
food,  and  a  greater  heat  more  water;  the  latter  acting 
injuriously,  by  producing  a  loss  of  the  heat  of  the  body, 
by  radiation  and  conduction  through  the  skin  of  the 
animal. 

It  was  found  that  more  than  one  half  of  the  organic 
substances  of  the  food,  was  lost  directly  or  indirectly 
through  the  perspiration ;  while  not  one  per  cent,  of  it 
was  absorbed  by  the  growth  of  new  wool. 

302.  Digestion  of  Crude  Flhre, 

Experiments  by  Dr.  Marcker,  of  Weende,  on  the  di- 
gestion of  hay  by  sheep  shows  that  60  per  cent,  of  crude 
fibre  was  digested;  that  the  40  per  cent,  remaining  un- 
digested, consisted  chiefly  of  lignin,  Avhich  contained  a 
large  portion  of  the  mineral  elements  of  the  food.  In  hay 
of  the  second  cutting  in  which  the  woody  fibre  had  not 
fully  matured,  68  per  cent,  was  digested.  Prof.  Wolff 
found  that  clover  cut  before  blossoming  was  about  one- 
sixth  more  digestible  than  that  which  had  passed  the 
bloom  before  it  was  cut. 

The  inference  is  clear,  that  the  increased  weight  which 
grass  acquires  in  ripening  is  from  lignin,  and  not  from  the 
digestible  cellulose.  On  this  account  it  has  been  esti- 
mated, that  grass  or  clover  cut  at  or  before  blooming  is 
worth  16  per  cent,  more  than  that  cut  after  maturity.  The 
nutriment  in  the  seed  would  change  the  result  somewhat. 

303.  Experiments  on  the  Production  of  Milk, 
The  following  table  shows  the  amount  of  milk,  dry 


350 


ANIMAL  NUTEITION. 


substance  in  the  milk,  etc.,  produced  by  different  classes 
of  cattle  food. 

Hay. 

Pounds  of  milk  daily. .  .16.15 

Containing  dry  sub- 
stance, per  cent  13.25 

Dry  substance  on  basis 
of  12  per  cent,  in  milk, 
containing  fat,  per  ct..  .4.18 

Albuminoids,  per  cent. . .  .2.74 

From  the  above  it  is  clear,  that  changing  the  propor- 
tion of  albuminoids,  carbo-hydrates,  and  fats,  has  but  little 
effect  on  their  relative  production  of  milk,  or  of  the  dry 
substances  in  the  milk. 

The  cows  were  fed  for  a  period  of  three  weeks,  on 
hay,  19^  lbs.  for  an  animal  weighing  1000  lbs.  and  in  that 
proportion  to  others.  The  next  period  hay  and  albumi- 
noids were  given,  and  so  on.  The  rations  were  increased 
17  per  cent.,  with  but  little  increase  of  the  amount  of  milk; 
but  with  richer  feeding,  there  was  a  slight  increase  of  the 
organic  substance  in  the  milk,  after  the  food  exceeded  a 
certain  minimum. 

It  was  also  found  that  changes  in  the  fodder  produced 
corresponding  changes  in  the  looks  and  weight  of  the  ani- 
mals. The  greatest  difference  between  the  largest  and 
smallest  daily  averages  was  7.4  lbs.  of  milk.  The  milk 
given  when  the  animals  were  in  the  best  condition  was 
richer  and  larger  in  amount,  and  also  contained  a  larger 
percentage  of  dry  substance.  This  latter  was  not  changed, 
however,  in  its  composition,  by  any  change  of  food,  but 
retained  the  same  percentage  of  fat,  sugar,  and  mineral 
matters.  Other  circumstances,  however,  as  the  advance 
of  time  from  calving,  and  peculiarities  of  individual  and 
race,  had  considerable  effect  upon  the  composition  of  the 
milk.    Certain  foods  Avould  sometimes  slightly  increase 


Hay  and  Hay  and  Hay  and  tto  , 
Albuminoids.  Starch.  Oil. 

...15.90. ...14. 68.... 15. 47... 13. 02 
. . .13.18. . . .13.33. . . .12.88. . .13.24 


....3.95  3.88  3.85. ...3.09 

....2.92  2.88  2. 80. ...2.86 


EXPEIilMEXTS  IN  BUTTER  MAKING. 


351 


the  quantity  of  fat  in  the  milk,  which  Wolff  attributed 
more  to  the  individual  than  to  the  food. 

The  lacteal  glands  have  heretofore  been  considered  a 
filter  for  the  milk,  simply,  secreting  it  as  other  glands  do 
other  substances  ;  but  Voit  ascertained  that  these  glands 
do  not  secrete  the  milk,  but  are  dissolved  into  the  milk 
themselves  by  fatty  degeneration,  the  milk  being  the 
glands  changed  into  a  liquid  form.  The  glands  require 
albuminoid  matters  for  the  cell  structure,  and  the  milk  is 
formed  of  them  only  as  they  form  new  cells.  The  food, 
then,  does  not  affect  the  milk,  only  as  the  lacteal  glands 
are  first  affected.  A  deficiency  in  the  albuminoid  matters 
of  the  food  would  produce  fewer  cells  and  less  milk. 
Hence,  a  coww^ell  fed  and  in  good  condition,  will  produce 
plenty  of  milk,  having  a  full  supply  of  food  to  build  up 
the  cells  of  the  lacteal  glands. 

Kuehn  infers  from  these  experiments  tliat  the  richest 
food  is  not  always  the  cheapest  for  cows.  Too  little  food, 
however,  is  even  worse  than  this.  A  fair  mean  is  the  best. 
A  butter  cow  cannot  be  made  a  cheese  cow  by  change  of 
food.  For  quality  of  milk  select  proper  breeds ;  for  quan- 
tity, good  milkers,  and  feed  well;  but  not  with  too  much 
rich  food. 

304.  Ex]periments  in  Butter  Making, 

It  is  an  old  opinion  that  butter  can  only  be  made  from 
sour  milk ;  and  chemists  have  accounted  for  it,  upon  the 
principle,  that  the  membrane  that  enveloped  the  butter 
molecules,  required  an  acid  to  set  them  free,  that  they 
might  combine  after  churning.  Mr.  Baumhauer  experi- 
mented with  fresh  milk,  and  came  to  a  different  conclu- 
sion. He  took  a  half  gallon,  and  divided  into  four  parts, 
placing  each  of  them  in  a  gallon  bottle.  One  was  left  as 
it  came  from  the  cow  ;  one  acidulated  with  lactic  acid  ; 
one  made  slightly  alkaline  with  carbonate  of  potash  (this 


352 


ANIMAL  NUTRITION. 


became  acid  during  manipulation),  and  the  fourth,  with, 
more  carbonate  of  potash,  which  remained  alkaline.  The 
temperature  was  about  70°  F.  These  bottles  were  shaken 
violently  by  four  men  for  one  minute,  and  then  examined 
after  each  shaking  for  eighteen  minutes.  Wart-like 
globules  at  first  adhered  to  the  glass,  which  continued 
to  increase  until  the  eighteen  minutes  had  transpired, 
when  yellow  butter  was  obtained  from  all  the  bottles  in 
masses  like  peas. 

Mr.  Baumhauer  says  that  the  lactic  acid  could  have  had 
nothing  to  do  with  dissolving  the  membranes,  and  he 
doubts  the  existence  of  such  membranes.  He  thinks  that 
temperature  has  everything  to  do  with  making  butter; 
and  that  churning  combines  the  floating  particles.  When 
the  milk  is  too  cold  no  butter  forms ;  when  too  warm  an 
emulsion  is  obtained,  which  hardens,  but  is  white,  and  not 
good  butter  at  a  lower  temperature.  He  contends  that  the 
temperature  for  making  butter  is  within  the  narrow  limits 
of  five  degrees,  between  65°  and  70",  and  the  souring  of 
the  milk  is  not  essential  to  it. 

305.  Preservation  and  Condensation  of  Milk, 

The  silicate  of  soda  will  preserve  milk,  and  keep  it  sweet 
for  five  or  six  days,  which  may  be  of  use  both  to  producers 
and  consumers  under  certain  circumstances.  To  cfiect 
this  purpose  dissolve  about  one  ounce  of  the  silicate  in 
a  quart  of  water  and  add  to  four  gallons  of  milk.  After 
being  kept  sweet  for  some  days,  the  cream  can  be  removed; 
the  remaining  fluid  will  be  alkaline,  without  a  trace  of 
casein. 

Artificial  milk  was  manufactured  during  the  siege  of 
Paris,  from  the  following  formula :  one  ounce  and  a  half 
of  sugar  was  dissolved  in  a  quart  of  water,  to  which  one 
ounce  of  dry  albumen,  made  from  the  white  of  eggs,  was 
added,  with  fifteen  to  thirty  grains  of  soda  crystals,  the 


FUEL  AND  FOOD  FOR  THE  ANIMAL  SYSTEM.  353 


whole  made  into  an  emulsion  with  one  to  two  ounces  of 
olive  oil.  Gelatine  may  be  substituted  for  albumen.  One 
firm  manufactured  132,000  gallons  of  milk  daily  by  this 
process  for  the  consumption  of  the  city. 

Condensed  milk  is  made  by  evaporating  the  watery  por- 
tions, thus  leaving  the  dry  substance,  which  is  put  up  in  air- 
tight boxes,  and  may  be  kept  an  indefinite  period.  A  small 
portion  of  this  powder  added  to  tea  or  cofi*ee  will  have 
the  same  efiect  as  cream.  It  is  very  useful  for  sea  voy- 
ages, and  any  condition  of  life  where  fresh  milk  cannot 
be  obtained.  It  is  particularly  adapted  to  the  rearing  of 
children  in  large  cities,  where  pure  fresh  milk  is  seldom 
found.  This  article  is  now  extensively  manufactured,  and 
is  becoming  a  considerable  item  of  commerce. 


CHAPTER  HI. 

FUEL  AND  FOOD  FOR  ANIMALS.  WHEAT  BRAN.  COTTON- 
SEED MEAL.  FODDER  CORN. 

306.  Fuel  and  Food  for  the  Animal  System, 

Much  that  is  called  food  for  animals,  is  nothing  but 
fuel.  We  must  distinguish  between  what  builds  up  and 
nourishes  the  animal  system,  and  that  which  simply  fur- 
nishes the  heat ;  and  while  being  important  to  the  life  and 
vigor  of  the  animal,  conduces  to  the  decay  and  decomposi- 
tion of  the  body,  instead  of  its  renewal. 

The  fuel  of  the  body  (its  heat  elements)  is  composed 
of  oxygen,  hydrogen,  and  carbon,  simply.  To  this  class 
belong  the  carbo-hydrates^  as  cellulose,  starch,  sugar,  etc.  ; 
the  vegetable  acids^  and  vegetable  oils. 

Animal  food  proper  (those  substances  which  build 
up  the  flesh,  and  nourish  and  develop  muscle,  blood,  and 


354 


ANIMAL  NUTRITION. 


nerves)  always  has  the  addition  of  nitrogen  to  the  other 
three  organic  elements.  They  are  classed  under  the  gen- 
eral term  of  albuminoids^  the  principal  of  which,  as  before 
stated,  are  albumen,  casein,  and  fibrin. 

But  while  there  is  no  nourishment  without  nitrogen, 
there  is  no  heat  without  carbon  and  oxygen,  and  no  water 
without  hydrogen  ;  all  of  which  are  important  to  the  ani-  i 
mal  health  and  life,  and  in  a  very  just  sense,  all  may  be 
classed  as  essential  constituents  of  animal  food. 

There  are  also  certain  mineral  elements  quite  as  essen- 
tial to  the  building  up  of  the  animal  frame,  as  phosphorus, 
calcium,  iron,  and  sulphur.  Without  the  two  former,  there 
could  be  no  bony  structure,  without  iron  no  healthy  blood, 
and  without  sulphur  and  phosphorous  it  is  doubtful  whether 
the  brain  and  nervous  system  could  so  well  perform  their 
offices. 

307.  Importance  of  Mixing  Cattle  Foods, 

A  perfect  food  for  animals  would  be  constituted,  then,  of 
a  proper  admixture  of  carbonaceous  and  nitrogenous  prin- 
ciples, containing  the  essential  mineral  elements  in  minute 
proportions.  Too  much  of  either  of  these  several  classes 
of  ingredients  would  render  it  imperfect. 

Thus,  it  has  been  well  established  by  scientific  experi- 
ments, that  feeding  on  clover  or  pea  vines  as  a  provender, 
with  corn,  is  not  as  healthy  as  a  fodder  or  hay  containing 
less  of  the  nitrogenous  or  nourishing  qualities. 

Wheat  and  oat  straw,  common  hay,  corn  fodder  (that 
is,  cured  corn  blades),  are  all  better  when  properly  saved 
than  the  richer  substances  above-mentioned,  to  mix  with 
corn  and  oats,  unless  the  amount  of  grain  is  lessened,  w^hich 
should  be  done  in  the  absence  of  less  nutritious  provender. 

The  better  process,  however,  because  healthier  to  the 
animal  and  cheaper,  would  be  to  save  the  less  nutritious 
fodders  to  be  mixed  and  fed  with  the  nutritious  grains. 


COTTON-SEED  MEAL. 


355 


and  let  the  clover  and  richer  provender  be  fed  to  cows, 
and  converted  into  milk  and  butter. 

308.  I^uti'itiousness  of  Wheat  Bran, 

It  has  long  been  the  opinion  of  chemists  that  the  bran 
which  is  rejected  as  food  for  man,  contains  much  that  is 
valuable  of  the  flesh-forming  and  blood-producing  consti- 
tuents. It  has  been  also  well  established  that  flour  is 
more  digestible  when  the  bran  is  retained. 

Recently  Dr.  Hubbell,  a  distinguished  pharmaceutist 
of  Philadelphia,  has  made  an  analysis  of  wheat  flour  and 
bran,  from  which  we  take  the  following  facts : 

From  every  100  pounds  of  wheat,  about  76  pounds  of 
flour,  and  20  pounds  of  bran  was  produced.  The  flour 
contains  of  tissue-making  elements  (gluten,  albumen,  etc.,) 
1.65;  of  phosphates  and  other  salts,  0.70;  total,  2.35  per 
cent.  The  bran  contains,  of  tissue-making  elements,  3.10; 
salts,  phosphates,  etc.,  7.05;  total,  10.15  per  cent.  That 
is,  for  purposes  of  nutrition,  the  bran  is  more  than  fourfold 
richer  than  the  flour,  or  (being  one-fourth  the  weight  of 
the  flour)  it  has  as  much  value  as  the  flour  itself.  Wheaten 
flour  of  the  miller  consists  chiefly  of  wheaten  starch,  while 
the  flesh-forming  element  of  the  grain,  with  the  blood  and 
bone-producing  constituents,  are  chiefly  rejected  in  the 
bran,  and  are  seldom  used  for  human  food,  through  tradi- 
tional ignorance  and  prejudice;  while  wheat  flour  is  doubly 
nutritious,  and  can  be  eaten  only  in  diminished  quantity, 
or  surfeit  will  be  the  result. 

Under  this  view  of  the  subject,  wheat  bran  constitutes 
a  very  important  cattle  food.  It  does  not  follow,  however, 
that  wheaten  flour  is  less  healthy  for  man,  because  less 
nutritious.    This  remains  to  be  demonstrated. 

309.    Cotton- Seed  Ileal 
We  have  incidentally  mentioned  the  cotton-seed  meal 


356 


ANIMAL  NUTEITION". 


as  a  cattle  food.  It  deserves  a  more  extended  notice,  as  it 
is  not  only  a  product  of  our  agriculture,  but  extensively 
used,  not  only  in  this  country  but  in  Europe. 

This  substance  is  prepared  from  cotton  seed  at  the  oil 
mills.  The  seed  are  first  decorticated,  the  kernel  ground 
to  powder,  thoroughly  cooked,  and  the  oil  extracted;  then 
made  into  cake,  and  ground  into  meal.  Before  being 
ground  it  is  worth  in  the  English  seaports  forty-five  dollars 
per  ton  in  gold. 

The  following  analysis  by  Prof.  Colton  shows  its  nu- 
tritive value  as  compared  with  American  linseed  cake: 

Linseed.      Cotton  Seed. 

Water   10.07  8.29 

Oil  12.38  16.05 

Albumen  22.36  41.25 

Gum  36.25  .17.44 

Fibre  12.69  8.92 

Mineral  matter  6.35  8.05 

The  albuminoids  of  the  cotton-seed  meal  have  6.58  of 
nitrogen,  and  the  ash  3.62  of  phosphate  of  lime,  showing 
it  to  be  a  good  fat  and  fiesh  former,  with  a  good  supply 
of  bone-forming  material. 

810.  Iwdder  Corn, 

For  the  production  of  provender,  we  are  satisfied  that 
no  plant  so  completely  secures  all  the  advantages  of  lux- 
uriant growth  on  thin  land,  and  the  amount  and  value 
per  acre  for  the  labor  expended,  as  the  maize.  It  should 
be  sowed  in  roAvs  about  three  feet  wide,  thick  enough  to 
minify  the  stalk,  cultivated  with  about  two  ploughings, 
cut  in  the  blossoming  of  the  tassel,  and  carefully  cured 
and  housed. 

After  cutting,  it  should  lie  on  the  ground  one  day,  and 
then  be  turned  over  and  lie  for  anotlier  day,  when  it  should 
be  taken  up,  tied  in  bundles,  and  put  in  shocks,  remaining 


VALUE  OF  CATTLE  FOODS  AS  PKOYENDER. 


357 


ten  or  fifteen  days,  or  until  the  stalk  is  cured  sufficient  to 
prevent  moulding  when  packed  away  in  the  barn.  As 
much  as  could  be,  should  be  cured  in  the  shade,  as  the 
blades  are  thereby  much  sweeter. 

The  proper  time  to  gather  fodder  corn  is  a  very  im- 
l^ortant  consideration.  If  cut  too  soon  it  has  not  sufficient 
of  the  albuminoids,  sugar  and  starch,  to  make  it  nutritive, 
and  thus  loses  much  weight  in  drying,  because  of  the 
water  in  it.  If  too  late,  the  cellulose,  which  is  for  the  most 
jDart  digestible,  is  changed  into  crude  fibre  or  lignin,  which 
is  mostly  indigestible  ;  and  the  epidermis,  which  otherwise 
would  be  soft  and  easily  masticated,  becomes  glazed  from 
deposits  of  silicate  of  lime,  which  is  not  only  indigestible, 
but  actually  hurtful  to  the  mucous  membrane  of  the  ali- 
mentary canal. 

The  stage  of  flowering  is  considered  the  best  time  to 
cut  hay  in  all  the  smaller  grasses,  as  thereby  the  most 
nutrition  is  secured.  In  reference  to  corn  fodder,  we  are 
disposed  to  think  a  little  earlier  than  this  will  secure  the 
most  important  advantages;  just  as  the  corn  is  beginning 
to  develop  the  tassel. 

Mr.  Holland,  a  Massachusetts  farmer,  experimented 
with  seventeen  cows  to  ascertain  the  value  of  this  food  in 
producing  milk.  After  feeding  them  on  fodder  corn,  and 
testing  the  quantity  of  milk  and  butter,  he  turned  them 
into  a  good  pasture  in  the  month  of  July,  and  there  was  at 
once  a  large  falling  off  in  milk.  During  August  he  soiled 
them  in  the  stable  with  fodder  corn,  and  there  was  a  gain 
in  the  production  of  milk.  In  September  they  were  turned 
into  the  mowing  (full  feed),  and  they  again  fell  off.  Mr. 
Holland  fed  sixty  or  seventy  pounds  daily  of  grass  fodder 
to  each  cow 

311.  Relative  Value  of  Cattle  Foods  as  Provender, 
The  following  analysis  by  Wolff  and  Knop,  of  products 


358 


ANIMAL  NUTEITION. 


used  as  provender,  shows  that  the  dry  corn-stalk  compares 
favorably  with  most  of  them,  as  to  the  amount  of  digestible 
food. 

Table  showing  the  relative  value  of  dry  cattle  foods, 
from  all  of  the  most  reliable  analyses  made: 


Substance. 

Albumi- 

Carbo- 

Fat. 

Crude 
Fibre. 

Digestible 
Food. 

Wheat  straw  

.  2.0. . 

..30.0..'. 

.1 

5.. 

..48.0. 

..33.5 

Pea  vines  

.  6.5.. 

..35.2... 

.2 

0.. 

..40.0. 

..43.7 

Oat  straw  

.  2.5.. 

..38.2... 

.2 

0.. 

..40.0. 

...42.7 

Corn  stalks  

.  3.0. . 

..39.0... 

.1 

1.. 

..40.0. 

...43.1 

Rye  straw  

.  1.5.. 

..27.0... 

.1 

.3.. 

..54.6. 

...29.8 

Barley  straw  

.  2.0. . 

..29.8... 

.1 

4.. 

..48.4. 

..33.2 

Meadow  hay  

.  8.2.. 

..41.3.. 

.2 

0. . 

..30.0. 

...51.5 

Red  clover,  full  blossom. 

.13.4.. 

..29.9... 

.3 

2.. 

..35.8. 

..46.5 

Red  clover,  ripe  

.  9.4  . 

..20.3... 

.2 

.0.. 

..48.0. 

..31.7 

Lucerne,  in  blossom. . . . 

.14.4.. 

..22.5... 

.2 

5.. 

..40.0. 

..39.4 

Timothy  

.  9.7.. 

..48.8... 

.3 

0.. 

..22.7. 

..61.5 

We  give  this  table  as  the  best  we  can  now  produce. 
We  are  well  convinced,  however,  that  a  stalk  of  maize,  cut 
and  matured  under  proper  auspices,  will  rate  still  higher 
than  the  showing  here  given. 

A  portion  of  the  crude  fibre  in  the  fourth  column  has 
been  found  to  be  digestible  also,  by  recent  experiments,  so 
that  the  last  column  may  be  put  down  as  an  approxima- 
tion only,  until  further  experiments  are  made. 


APPENDIX. 


APPENDIX. 


I. 

THE    COTTON  PLANT, 

GOSSYPIUM  HERBACEUM. 

1.  Its  History. 

The  cotton  plant  was  known  to  the  ancients,  being  cultivated 
for  the  value  of  its  wool.  Gossypiuni  was  the  name  given  to  it  by 
Pliny. 

Herodotus,  450  years  B.  C,  spoke  of  the  trees  of  India  bearing 
fleeces  more  delicate  than  those  of  sheep.  Caesar  covered  the 
Forum  with  India  cotton,  and  the  Sacred  Way  from  his  palace  to  the 
Capitoline  Hill ;  and  tents  were  made  for  his  soldiers  of  it,  as  well  as 
for  those  of  Greece. 

Pliny  spoke  of  wool-bearing  trees  in  Upper  Egypt,  produciug 
fruit  like  a  gourd,  as  large  as  a  quince,  ripening  and  bursting  into 
downy  wool  from  which  costly  fabrics  were  made. 

Cotton  was  an  article  of  commerce  at  the  beginning  of  the  Chris- 
tian era,  India  being  the  main  source  of  supply.  It  was  intro- 
duced into  Spain  as  early  as  the  tenth  century  by  the  Moors,  and 
thence  into  Sicily  and  Turkey. 

Columbus  found  the  cotton  plant  growing  wild  in  Hispaniola. 
Later  explorers  found  it  on  the  Mississippi  and  its  tributaries.  The 
Mexicans  and  Peruvians  manufactured  it  into  cloth,  long  before  the 
discovery  of  America. 

Cotton  seed  was  first  planted  as  an  experiment  in  1621,  in  the 
United  States,  and  was  known  as  a  garden  plant  in  1736.  The  first 
export  on  record  was  seven  bags  of  cotton  wool  from  Charleston, 
S.  C,  in  1748. 

Eli  Whitney,  a  native  of  Massachusetts,  while  residing  on  St. 
Simon's  Island,  Georgia,  in  1793,  invented  the  first  cotton  gin  for 
separating  the  lint  from  the  seed. 


362 


APPENDIX. 


2.  Its  HaHtudes. 

The  cotton  is  a  sun  plant,  flourishing  only  in  warm  climates, 
turning  its  head  to  the  east  in  the  morning,  as  if  to  seek  the  first 
warm  beams  of  the  sun,  and  following  its  circuit  during  the  day 
with  the  same  faithful  inclination  till  it  sinks  in  the  west. 

According  to  botanists  there  are  fifteen  or  twenty  species.  It 
occurs  as  a  herb  in  the  Cotton  States  proper.  In  the  extreme  South 
it  assumes  the  proportions  and  habitudes  of  a  shrub.  In  Central 
America  it  is  arborescent,  developing  into  a  small  tree. 

It  has  a  tap  root  penetrating  deep  into  the  subsoil,  and  on  this 
account  suffers  less  from  drought,  and  is  less  exhaustive  of  the  soil. 
It  nevertheless  has  many  lateral  roots,  which  branch  out  into  in- 
numerable fibrils  permeating  the  surface  soil  in  quest  of  food. 

Its  fruit,  the  boll,  is  contained  in  an  egg-shaped  capsule,  having 
from  three  to  five  cells,  in  which  are  contained  the  seeds,  and  a 
tomentose  wool  which  is  properly  the  outer  coat  of  the  seed.  This 
is  the  lint,  or  fibre,  which  furnishes  clothing  to  the  civilized  world. 
In  its  origin,  progress,  and  full  development,  the  cotton  boll  is  a 
fruit,  only,  unlike  most  fruits,  it  is  not  intended  to  eat,  but  to  wear. 
The  nearest  approach  we  have  known  to  its  being  classed  with 
edibles,  was  the  substitution  of  the  young  fruit  by  a  lady  for  pickles. 

The  blossom  opens  white  or  cream-colored  the  first  day,  resem- 
bling the  okra  and  hollyhock,  which  belong  to  the  same  class  in  the 
natural  system ;  it  turns  red  the  second  day,  and  drops  off  the  third, 
leaving  the  young  boll  enveloped  in  the  calyx. 

Cotton  will  not  flourish  north  of  an  isothermal  line  of  It 
has  been  grown,  under  the  influence  of  stimulating  fertilizers,  as 
far  north  as  the  fortieth  degree  :  the  36th,  however,  may  be  deemed 
its  extreme  latitudinal  limit.  The  cotton  belt  of  the  United  States 
lies  between  the  31st  and  34th  degree  of  north  latitude.  North  of  this 
the  seasons  are  too  short ;  south  of  it,  the  crop  is  very  uncertain, 
owing  to  the  heavy  rains,  depredations  of  caterpillars,  etc. 

3.  Proximate  Analysis  of  Cotton  Seed, 

In  1,000  lbs.  of  seed  cotton  there  are  approximately  333.3  of  lint, 
333.3  of  hull,  and  333.3  of  kernel.  This  latter  contains  40  per  cent, 
of  oil,  which  has  a  specific  gravity  of  0.933,  the  same  as  whale  oil. 
It  is  manufactured  extensively  in  some  of  the  Western  cities,  is  use- 
ful in  the  arts  for  lubricating  machinery,  burning  in  lamps,  and 


APPENDIX. 


363 


making  soap.  It  also  has  been  eaten  as  salad  oil  as  a  substitute  for 
olive  oil. 

The  residue  constitutes  the  cotton-seed  oil-cake  of  commerce. 
It  ranks  high  as  a  fertilizer  and  food  for  cattle.  It  contains  1.1 
per  cent,  of  sugar  and  35  of  gum.  Iodine  gives  no  evidence  of  the 
existence  of  starch  in  it.  (Jackson.) 

Taking  the  principles  of  nutrition,  embracing  the  fat  formers 
and  flesh  formers  both,  cotton-seed  cake  stands  as  follows  compared 
with  these  substances.  (Colton.) 

Corn  Meal  81.1  Oatmeal  69.1 

Wheat  Flour.  77.7         Peas  65.0 

Cotton-seed  Cake  74.7         Beans  63.7 

Linseed  70.8  Buckwheat  61.1 

Rye  Meal  70.1  Red  Clover  Hay  41.2 


4.  Spontaneous  Combustion  of  Cotton. 

It  has  been  long  believed  that  under  certain  circumstances  seed 
cotton  in  bulk  can  be  made  to  produce  heat  enough  to  cause  com- 
bustion ;  and  thus  very  much  loss  of  property  has  been  caused  by 
the  burning  of  gin-houses. 

Gallately  found  that  cotton  soaked  in  boiled  linseed  oil,  and  the 
temperature  raised  to  170^,  will  then  begin  to  generate  heat ;  and 
in  one  hour's  time  will  acquire  a  temperature  of  350°  and  take  fire. 
Raw  linseed  oil  required  five  hours,  rape  oil  ten,  olive  oil  six,  lard 
oil  four,  and  seal  oil  about  two  hours.  Castor  oil  would  produce  a 
slight  charring  in  two  days  ;  and  sperm  oil  produced  negative 
results. 

Now  it  is  known  that  when  seed  cotton  is  put  in  bulk  after  be- 
ing picked,  even  if  sunned,  it  undergoes  high  heat;  and  when  a 
little  damp,  as  is  too  often  the  case,  the  seeds  swell  and  burst  in 
some  instances,  and  an  oily  substance  exudes.  This  is  particularly 
true  of  the  lower  stratum  near  the  floor.  We  have  seen  the  whole 
of  this  part  of  the  bulk  glued  together  by  the  oil,  and  the  seeds 
rotted  and  blackened,  as  if  charred. 

Is  it  not  probable,  that  the  cotton-seed  oil  thus  eliminated  by  the 
heat,  produces  the  same  effect  demonstrated  by  the  experiment  of 
Gallately  with  other  oils,  and  that  this  is  a  prolific  source  of  the 
burning  of  so  many  cotton-houses,  now  attributed  to  incendiarism? 
The  subject  demands  further  demonstration. 


364 


APPENDIX. 


5.  Ultimate  Analysis  of  the  Cotton  Plant. 

From  analysis  of  Prof.  H.  C.  White,  the  hull  of  cotton  seed  con- 
tains 0.960  of  nitrogen.  As  the  cotton-seed  cake  constitutes  30  per 
cent,  of  the  whole  seed,  we  have  in  hull,  and  kernel  combined, 
analysis  by  Jackson,  nitrogen  3.80  ;  by  Ville,  3.06  ;  by  Colton,  2.45. 
The  average  of  these  three  chemists,  taking  White's  analysis  of 
hull  as  the  basis,  makes  the  amount  of  nitrogen  in  the  whole  seed, 
capsule  and  all,  as  used  by  farmers  for  manure,  3.10  per  cent. 

It  is  proper  to  state  that  the  analysis  of  M.  Ville  was  made 
simply  of  the  grain  or  kernel,  which  constitutes  just  50  per  cent, 
of  the  whole  seed.  The  analysis  of  the  hull  by  Prof.  White  wag 
added  to  this,  which  makes  tlie  figures  in  the  second  column. 

An  analysis  of  all  the  different  parts  of  the  cotton  plant  has 
been  made  by  several  chemists.  We  present  a  table  from  an  ave- 
rage of  these  analyses,  which  shows  how  much  of  all  the  mineral 
elements  is  required  to  make  a  bale  of  cotton  weighing  500  lbs. 
of  lint  or  fibre.  We  assume  that  it  will  take  1,000  lbs.  of  seed,  500 
lbs.  of  leaves,  1,500  lbs.  stems,  500  lbs.  of  roots,  and  500  lbs.  of  cap- 
sules or  burrs.  Profs.  Jackson,  Ville,  and  White  gave  analyses  of 
the  lint,  stems,  leaves,  and  roots,  of  which  we  take  the  average. 


The  bolls  were  an 

alyzed 

by  Prof 

.  W 

hite 

only. 

In  500 

In  1,000 

In  1 

,500 

In  500 

In  500 

In 

500 

In 

whole 

lbs.  of 

lbs.  of 

lbs. 

of 

lbs.  of 

lbs.  of 

lbs 

.  of 

plant 

lint. 

seed. 

stems. 

leaves. 

burrs. 

roots. 

for  one 

bal 

e. 

Phosphoric  Acid. . 

.0.65. 

.12.17. 

.  5. 

62. 

.  5.27. 

.  4.46. 

.1. 

83. 

.30. 

00 

Potash  

,.2.11. 

.11.24. 

.11. 

,46. 

.  9.74. 

.  9.28. 

.5, 

.81. 

.49. 

64 

Lime  , 

..1.51. 

.  3.84. 

.13 

.23. 

.18.79. 

.17.70. 

.5 

.64. 

.60. 

,70 

Magnesia  

.0.57. 

.  5.01. 

.  4. 

,45. 

.  3.13. 

.  3.99. 

.2. 

,03. 

.18. 

,59 

Sulphuric  Acid. . , 

..0.31. 

.  1.89. 

2 

.49. 

.  7.30. 

.  8.61. 

.1, 

.12. 

.21. 

,22 

Oxide  of  Iron  

..0.15. 

.  0.66. 

.  0, 

.94. 

.  2.97. 

.  3.32. 

.1, 

.74. 

.  9. 

,78 

Chlorine.  , 

..0.45. 

.  0.61. 

.  3, 

.18. 

.  3.44. 

.  2.67. 

.1. 

,99. 

.12. 

34 

Soda. ,  

..0.53. 

.  1.44. 

.  4, 

.56. 

.  5.50. 

.  5.74. 

.2, 

.88. 

.20. 

,65 

Silica  

..0.09. 

.  0.39. 

.  2. 

,14, 

.  4.48. 

.  9.25. 

.1. 

.98. 

.18, 

23 

6.  Exhaustion  of  Minerals  from  Soils  oy  Cotton. 

The  above  table  shows  at  a  glance  how  much  of  each  mineral 
ingredient  would  be  requisite  in  the  soil  to  make  a  bale  of  cotton 
weighing  500  lbs.    When  one  bale  is  made  to  the  acre,  it  represents 


APPENDIX. 


36.5 


the  amount  taken  from  an  acre ;  if  only  two  are  made,  eacli  item  can 
be  lialved  ;  if  tliree,  one-tliird  of  each  can  be  taken,  and  so  on ;  and 
a  planter  can  thus  calculate  his  annual  loss.  In  this  calculation  he 
can  always  leave  out  silica  and  oxide  of  iron  as  being  inexhaustible 
in  all  soils.  Of  the  remaining  seven,  a  soil  properly  treated  would 
rarely  need  replenishing  except  in  one  or  two  instances. 

By  treating  the  soil  properly  we  mean,  that  cattle  should  not 
depredate  upon  the  cotton  fields  in  the  winter,  carrying  off  stems, 
leaves,  and  capsules;  that  instead,  the  stalks  should  be  knocked 
down,  the  burrs  scattered  and  ploughed  in,  that  they  may  rot,  and 
furnish  nitrogen  as  well  as  mineral  food  to  the  next  crop ;  that  the 
seed  should  all  be  returned  to  this  or  some  other  field  on  the  farm. 
Under  this  treatment  nothing  w^ould  be  permanently  lost  but  th<3 
lint,  which  for  every  acre  of  land  producing  a  half- bale  of  cotton 
(more  than  an  average),  would  carry  off  only  one-third  of  a  pound 
of  phosphoric  acid,  one  pound  of  potash,  three- fourths  of  a  pound  of 
lime,  one-fourth  of  a  pound  of  magnesia,  one-sixth  of  a  pound  of 
sulphuric  acid,  and  less  than  one-fourth  of  a  pound  of  chlorine, 
with  a  little  more  of  soda. 

The  mineral  exhaustion  from  such  a  farm  would  hardly  be 
worth  mentioning,  and  Avould  not  require  any  replenishing  for 
many  years,  if  we  except  phosphoric  acid  ;  from  the  fact  that  while 
there  would  be  quite  enough  remaining  from  the  debris  of  the  min- 
eral elements  of  the  plants,  much  of  it  would  be  thrown  into  an 
insoluble  state,  by  uniting  with  iron,  alumina,  and  lime  itself,  and 
thus  remain  unavailable  until  dissolved  by  acids  or  ammonia.  Of 
all  the  other  mineral  elements  we  may  safely  say  that  they,  in 
their  very  decomposition,  are  readily  placed  in  suitable  forms  for 
assimilation  as  plant-food. 

If,  however,  we  count  the  seed  with  the  lint,  as  being  taken  from 
the  soil  (which  is  the  proper  way),  we  have  about  six  pounds  and 
one-third  of  the  invaluable  element  of  phosphoric  acid  and  seven 
and  a  half  of  potash  lost  to  the  soil  annually  in  the  750  lbs.  of  seed 
cotton  from  one  acre. 

7.  Cotton  Ciilture. 

As  to  the  culture  of  cotton,  it  is  proper  to  say  this  much  :  The 
best  soil  is  a  clay  loam,  which  should  be  thrown  up  in  beds  to  pro- 
tect from  the  cold  sobby  rains  of  spring*.  A  silicious  soil  on  a  clay 
subsoil  is  perhaps  better,  as  it  is  easier  cultivated  and  quite  as  pro- 
ductive. ^ 


366 


APPENDIX. 


Cotton  rows  should  not  be  too  wide,  as  the  fibrils  will  not  per- 
meate the  whole  soil,  and  get  the  same  amount  of  nutriment.  Our 
experiments  show  that  on  a  thin  soil,  two  and  a  half  feet  is  the  best 
width.  Three  to  three  and  a  half  for  better  soils.  One  stalk  in  a  hill 
is  better  than  two,  when  left  the  usual  distance  of  a  foot  or  less 
apart.  Of  a  very  seasonable  year  thick  planting  may  produce  more, 
but,  when  the  drought  comes  (as  it  is  apt  to  do,  in  July  or  August), 
the  fruit  falls  much  more  rapidly  from  the  thick  planting.  You 
will  observe  that  one  stalk  at  such  times  standing  by  itself  will 
remain  green  and  flourishing  and  retain  its  fruit,  while  the  thick 
planting  wilts  and  the  fruit  dries  up  for  lack  of  moisture. 

Having  laid  off  your  cotton  rows  with  a  scooter,  follow  with  a 
long  shovel,  in  the  bottom  of  which  deposit  from  100  to  200  lbs. 
per  acre  of  the  best  ammoniated  superphosphate ;  list  on  with  a 
scooter,  and  then  with  a  turning  shovel,  finishing  the  middle  with  a 
common  shovel.  You  now  have  a  good  bed  for  your  cotton,  which 
is  important,  as  we  have  repeatedly  tested,  to  relieve  the  young 
phint  from  the  cold  sobby  rains  of  spring,  by  draining,  as  well  as 
afford  as  much  warmth  and  sunshine  to  them  as  possible. 

The  first  ploughing  should  be  as  deep  as  possible ;  after  that, 
shallow  culture  with  a  sweep  to  the  end  of  the  chapter  ;  as  break- 
ing the  roots  after  the  fruit  begins  to  form  will  be  fatal  to  a  portion 
of  it  at  least.  It  should  be  cultivated  as  rapidly  as  possible,  the 
grass  kept  out  with  the  hoe,  as  not  only  does  it  choke  up  and  retard 
the  growth  of  the  cotton,  but  steals  a  good  portion  of  the  ammonia 
and  other  soluble  matters  from  the  fertilizer  and  the  soil,  which 
would  otherwise  be  appropriated  to  the  plants. 

Too  much  care  cannot  be  taken  in  hoeing  cotton,  as  the  least 
bit  of  epidermis  knocked  off  is  apt  to  generate  a  disease  known  as 
sore  sliiii,  which  cripples  the  plant  for  life,  and  renders  it  compara- 
tively unproductive.  It  is  believed  that  this  disease  sometimes 
assumes  the  character  of  an  epidemic,  especially  on  poor  land,  re- 
sulting from  the  injuries  of  insects. 

8.  Early  and  Late  Planting  of  Cotton, 

The  proper  time  to  plant  cotton  is  when  the  ground  has  become 
sufficiently  warm  to  germinate  the  seed  promptly,  and  bring  up  a 
healthy  plant.  This  would  be,  in  the  cotton  belt  proper,  from  the 
middle  of  April  to  the  middle  of  May. 

The  only  argument  in  favor  of  early  planting  is  that  it  requires 


APPENDIX. 


367 


considerable  moisture  to  germinate  the  seed,  and  often  the  month 
of  May  is  so  dry  that  ]ate  planting  fails  to  secure  a  good  stand. 
This  can  generally  be  obviated,  however,  by  covering  the  seed  vritli 
two  scooter  furrows,  and  then  striking  off  with  a  board,  after  the 
seed  has  taken  root. 

One  great  advantage  in  late  planting,  especially  with  our  demo- 
ralized labor,  is  that  it  destroys  a  coating  of  grass,  which  is  apt  to 
infest  and  injure  early  cotton.  This  is  especially  the  case  where 
fertilizers  are  used.  The  stimulus  given  to  the  plant  by  concen- 
trated manures  will  push  it  forward,  and  much  less  of  the  ammonia 
will  be  lost  by  going  into  the  grass,  in  late  plantings. 

The  best  general  rule  to  lay  down  is  to  plant  thin  lands  as  early 
as  possible,  and  rich  lands  or  those  highly  fertilized  later,  as  such 
lands  can  be  cultivated  with  about  half  the  labor  as  when  planted 
early. 

In  1873  we  experimented  with  early  and  late  planting,  with  the 
results  given  in  the  table  below.  The  fertilized  rows  had  at  the 
rate  of  250  lbs.  of  ammoniated  superphosphate  per  acre.  The  last 
planting  was  injured  by  the  caterpillar. 

Table  showing  the  comparative  production  of  cotton  in  early, 
medium,  and  late  planting,  with  and  without  fertilizers,  in  ounces  : 

1st     2d  3d 
Pick-  Pick-  Pick 
ing.     ing.  ing. 

Planted  10th  April,  5  rows  fertilized. . .  .534.  .497. .  38 
"         "  5  rows,  no  manure.  .211.  .380. .  65 

Planted  10th  May.  .5  rows  fertilized  479.  .588. .  45 

"  5  rows, no  manure.  .230.  .478. .  80 

Planted  24th  May.  .5  rows  fertilized         00.  .472.  .245 

"         "  5  rows,  no  manure. .  00..  215,.  154 

Thus  cotton  planted  10th  of  May  without  fertilizers,  excelled 
that  planted  a  month  earlier,  when  the  ground  was  cold.  The  fer- 
tilized cotton  made  but  little  difference,  owing  to  the  warmth  im- 
parted by  the  manure.  This,  however,  might  be  different  other 
years,  and  cannot  be  laid  down  as  a  universal  rule. 

9.  Fertilizers  for  Cotton. 

The  best  fertilizer  on  all  worn  soils  is  an  ammoniated  super- 
phosphate, containing  from  two  to  three  per  cent,  of  ammonia,  and 
fifteen  to  twenty  of  soluble  bi -phosphate  of  lime.    The  organic 


-  Total.^^'- J^^' 
acre. 

..1,069..  801 
. .  656.. 492 
..1,112.. 834 
. .  788.. 591 
. .  717.. 538 
. .   366.. 276 


368 


APPENDIX. 


matter  sliould  be  husbanded  in  the  soil,  as  helping  to  retain  mois- 
ture and  ammonia,  and,  by  its  decomposition,  furnish  carbonic  acid 
as  a  food,  and  a  solvent  to  prepare  food  for  the  plants. 

A  small  amoant  of  potash  (chloride  of  potassium),  soda  (either 
the  sulj)hate  or  chloride),  and  chlorine  might  be  added,  as  there  are 
some  soils  in  which  these  salts  might  be  deficient. 

Numerous  experiments,  too  tedious  to  detail  here,  conducted  for 
the  last  twenty  years,  on  the  worn  soils  of  Middle  Georgia  by  the 
author,  has  clearly  demonstrated  that  the  proper  application  of 
nitrogen,  with  soluble  phosphate  of  lime,  will  restore  these  soils  up  to 
and  above  their  pristine  fertility,  at  least  in  the  production  of  cotton. 

In  order  to  do  this,  however,  the  soil  must  have  the  concurrent 
aid  of  organic  matter,  not  simply  for  iis  mechanical  and  physical 
qualities,  but  because  it  furnishes  some  nitrogen,  and  all  the  other 
mineral  ingredients,  in  conditions  available  as  plant-food.  The 
phosphoric  acid  being  the  only  one  not  furnished  in  sufficient  quan- 
tities and  in  a  proper  form,  to  make  a  vigorous  and  fruitful  cotton 
plant.  Science  has  supplied  this  in  the  commercial  superphosphates 
now  so  extensively  used. 

Experiments  illustrating  these  facts  have  already  been  given 
in  Part  VII.  of  this  work. 

10.  The  Cotton  Caterpillar. 

The  coUon  caterpillar  (Anomis  xylinae),  so  much  dreaded  by  the 
planter,  is  green,  double  striped  with  black  on  the  back,  grows 
from  an  inch  and  a  half  to  two  inches  in  length,  has  sixteen  legs; 
the  foremost  prop  legs  are  shorter  than  the  rest,  and  they  crook  their 
backs  in  creeping.  They  have  six  pectoral,  eight  ventral,  and  two 
anal  feet.  (Barbee.) 

This  army  worm  is  peculiar  to  the  cotton-plant,  and  found  only 
as  far  as  it  is  cultivated.  It  is  transformed  into  an  imperfect 
cocoon,  from  whence  issues  an  olive-brown  moth,  called  Noctua 
xylina,  by  Mr.  Say.  The  wings  of  this  fly  have  a  grayish  cast,  the 
upper  wings  being  a  little  reddish,  with  a  dark  spot  and  a  small 
white  centre  in  each. 

They  are  found  in  the  daytime  resting  on  walls  and  ceilings 
of  rooms,  where  they  remain  motionless  until  night  approaches, 
when  they  fly  ofi"  to  the  cotton  fields,  where  they  deposit  their  eggs, 
principally  on  the  under  side  of  the  leaVes,  but  often  on  the  outer 
calyx,  rarely  upon  the  stem. 


APPENDIX. 


369 


The  eggs  are  very  small,  round,  and  flat,  and  appear  ribbed  under 
the  microscope.    It  takes  from  fourteen  to  twenty  days  for  them 
j     to  hatch  out,  depending,  no  doubt,  much  on  the  state  of  the 
weather. 

When  hatched,  the  young  caterpillars  begin  at  once  to  feed  on 
the  soft,  fleshy  parts  of  the  leaves  ;  and  it  is  very  noticeable  that 
they  eat  up  the  young  stalks  first,  if  there  are  any,  and  avoid  the 
ridges  in  time  of  drought,  taking  the  valleys  and  moist  spots  where 
the  plants  are  full  of  sap,  and  in  a  growing  state.  For  the  same 
reason,  they  avoid  fertilized  crops,  and  parts  of  crops  which  have 
been  stimulated  to  an  earlier  and  more  mature  growth.  When, 
however,  their  numbers  increase  and  as  they  themselves  grow 
older,  they  attack  the  riper  stalks,  and  even  stems  and  young  bolls, 
leaving  but  little  besides  the  bare  stalk.  After  finishing  one  field, 
they  instinctively  march  to  the  next  one  adjacent,  never  mistaking 
their  course.  Hence  they  have  been  called  the  cotlon  army 
worm. 

Mr.  William  Jones,  of  the  Southern  Gtdtimtor^  is  of  opinion  that 
the  reason  why  they  trouble  the  northern  cotton  belt  so  little,  is 
owing  to  the  fact  that  when  they  hatch  out  early  in  the  spring, 
t  ley  are  killed  off"  by  subsequent  spells  of  cold  weather,  which  do 
not  occur  further  south.  Hence,  they  follow  very  cold  and  sharply 
defined  winters,  as  that  of  1872  and  '73,  in  this  region  ;  which  was 
the  second  year  in  which  they  ever  made  any  considerable  depre- 
dations in  the  upper  cotton  belt. 

They  moult  several  times  before  their  full  growth,  lying  in  a 
quiescent  state  for  a  day  or  two,  and  coming  out,  leaving  their  old 
skins  behind,  to  attack  with  fresh  vigor  the  remaining  leaves  of 
their  favorite  plant.  The  caterpillars  of  the  second  and  third  gen- 
erations are  much  darker  than  the  first. 

They  cease  to  feed  in  fifteen  and  twenty  days,  and  begin  to  form 
a  loosely  spun  cocoon,  doubling  down  the  leaf  over  them,  assuming 
the  chrysalis  state,  which  remains  about  fifteen  days  more  before 
the  moth  appears.  This,  however,  may  be  delayed  by  cold  spells  ; 
the  one  before  winter  sets  in  remaining  till  the  succeeding  spring. 

The  damage  done  to  the  planting  interest  by  this  insignificant 
worm  some  seasons,  is  truly  astounding.  Prof.  Wiley,  of  St.  Louis, 
estimated  the  loss  in  a  single  fortnight  of  1873  at  $20,000,000.  It 
generally  begins  its  ravages  in  the  Southwestern  States  as  early  as 
the  latter  part  of  July,  and  continues  there  until  frost.  Within 


370 


APPENDIX. 


this  time  several  generations  make  their  appearance,  each  succeed- 
ing one  increasing  largely  in  numbers. 

Various  remedies  for  this  formidable  enemy  of  the  cotton  plant 
have  been  suggested.  The  most  effective  seems  to  be  the  Paris 
green,  which  contains  varied  proportions  of  arsenious  acid,  and  on 
this  account  should  be  used  cautiously.  Mixed,  however,  with 
about  thirty  parts  of  flour  or  land  plaster,  and  put  in  a  tin  box  with 
a  fine  sieve  attached,  the  box  fixed  to  a  stick  of  several  feet  length, 
and  held  in  the  left  hand  over  the  cotton  row,  the  operator  can 
walk  as  fast  as  he  chooses,  and  with  repeated  taps  with  a  stick  in 
his  right  hand  on  the  box,  go  over  a  number  of  acres  in  one  day. 
A  very  small  dusting  will  suffice :  thirty  pounds  of  the  mixture  at 
a  cost  of  25  cents  will  answer  for  several  acres.  With  this  remedy 
applied  on  tlie  first  generation,  it  would  seem  that  planters  have 
their  enemy  very  much  in  their  own  hands. 

11.  Cotton  Louse,  Aphis. 

The  cotton  louse  infests  the  cotton  plant  some  seasons,  doing 
considerable  damage,  by  crisping  up  the  leaves,  causing  them  to 
turn  yellow  and  drop  off.  These  insects  like  the  fresh  buds  and 
and  tender  plants,  and  are  more  numerous  during  damp,  cloudy 
weather.  In  sunshiny  days  they  get  under  the  leaf,  and  continue 
their  depredations  by  piercing  the  parenchyma  or  outer  coating, 
from  which  they  suck  the  juices  of  the  plant. 

The  young  lice  are  very  small,  being  about  one  line  in  length, 
of  a  greenisli  color,  turning  darker  as  they  grow  older.  They  are 
remarkably  prolific,  as  Reaumur  has  j^roved  that  one  individual  of 
this  genus  in  five  generations  will  sometimes  become  the  pro- 
genitor of  five  or  six  millions  of  descendants. 

But  for  the  fact  that  they  have  many  enemies,  and  are  easily 
killed  by  frost  and  sudden  changes  of  weather,  their  increase  would 
be  incalculable.  The  lady-bird,  the  lace-fly,  the  syrphus,  and  the 
ichneumon  are  its  principal  destroyers,  and  upon  these  formidable 
allies  the  planter  has  to  rely  for  their  destruction,  as  they  come  at 
a  time  and  in  such  quantities,  that  it  would  not  pay  him  to  attempt 
their  extirpation  by  tedious  and  doubtful  methods  of  sprinkling 
powders  and  solutions. 

12.  The  Cut-Worm,  Agrotis. 
The  cut-worm^  a  ground  caterpillar,  probably  the  same  as  \  he 


APPENDIX. 


371 


cabbage-worm  of  the  North  and  Europe,  which  comes  from  a  moth, 
Agrotis  suffusa  or  telifere  (Harris),  sometimes,  though  rarely,  pro- 
duces considerable  damage  to  the  cotton  crop.  It  comes  up  from 
the  ground  during  the  night,  and  eats  up  leaves,  buds,  and  limbs, 
frequently  leaving  notluDg  but  the  bare  stem. 

Lands  which  have  been  lying  fallow  seem  mostly  infested  with 
them,  and  probably  a  good  winter  ploughing  would  prove  a  partial 
relief. 

The  best  remedy,  we  believe,  for  them  and  most  other  insects,  is 
high  fertilization,  as  such  fields  are  apt  to  overcome  damages  which 
would  prove  fatal  on  poor  soils. 

I 

I  13.  The  Boll  Worm,  Heliothes  armigera. 

r  The  hall  worm  is  another  enemy  of  the  cotton  plant  which  does 
considerable  damage  during  some  seasons.  The  egg  is  laid  on  the 
tender  fleshy  substance  of  the  calyx,  where  the  young  worm  begins 
to  feed  as  soon  as  hatched.  They  pierce  the  enclosed  flower-head, 
and  the  young  boll  itself,  causing  them  to  die  and  fall  off"  in  a  short 
time.  The  number  of  buds  destroyed  by  this  worm  some  years  is 
much  greater  than  might  be  supposed,  as  they  fall  off  when  so 
small,  and  wither  on  the  ground  without  exciting  much  notice. 
The  worm  has  the  faculty  of  escaping,  generally  before  the  boll  is 
detached. 

This  worm  has  the  power  of  suspending  itself  by  a  thread  like 
a  spider,  if  brushed  from  a  leaf  or  boll  on  which  it  rested.  After 
moulting  several  times,  it  attains  its  full  size.  It  is  smaller  than 
the  army  worm,  some  of  them  green  and  some  brown  with  dark 
spots,  and  slightly  covered  with  short  hairs.  It  has  the  same  num- 
ber of  feet,  and  the  same  kinds  as  the  cotton  caterpillar  ;  but  a 
gradual  even  motion  very  unlike  the  looping  gait  of  the  former. 

The  upper  wings  of  the  moth  are  yellowish  or  reddish,  with 
sometimes  a  shade  of  green.  The  under  wings  are  lighter  colored. 
They  multiply  very  rapidly  ;  one  female  containing  about  five  hun- 
dred eggs,  would,  as  they  produce  three  generations  in  one  year,  if 
they  all  lived,  infest  a  field  with  forty-two  billions  of  worms.  But 
many  of  them  are  consumed  by  the  birds  and  other  insects  which 
prey  upon  them. 

i         The  full  grown  caterpillar,  when  it  ceases  to  eat,  descends  into 
the  ground,  where  it  constructs  a  silky  cocoon,  interwoven  with 
^     particles  of  gravel  and  earth,  and  changes  into  a  bright  chestnut- 


372  APPENDIX. 

brown  chrysalis,  appearing  as  perfect  moths  in  seven  or  eight  weeks. 
(Barbee.) 

14.  Other  Insects  and  Remedies. 

Many  other  insects  of  minor  importance  infest  the  cotton  plant, 
doing  but  little  damage  ;  as  the  tortrix,  or  leaf-rolling  caterpillar, 
the  leaf-hopper  (tettigonia),  the  red  spider  (acarus),  the  stinging 
caterpillar,  produced  from  the  corn,  emperor  moth,  (Saturnia  io).  It 
feeds  upon  the  foliage  both  of  corn  and  cotton,  but  never  occurs  in 
large  numbers.  Also  the  red  bug,  or  cotton  stainer  (Lygaeus), 
which  does  considerable  damage  farther  south,  by  staining  the  cot- 
ton fibre  in  the  bolls. 

A  number  of  methods  have  been  suggested  for  destroying  insects 
injurious  to  the  cotton  plant,  but  most  of  them  are  of  doubtful 
utility.  Cobalt  and  other  poisons  have  been  sprinkled  on  the 
blooms  of  plants  known  to  be  frequented  by  the  moths,  for  the  pur- 
pose of  destroying  them ;  but  we  regard  all  such  remedies  as  very 
objectionable,  as  more  useful  insects  might  be  destroyed  by  such  an 
indiscriminate  application  of  poison  than  of  the  other  class.  Even 
the  use  of  Paris  green  as  a  remedy  for  the  cotton  caterpillar,  might 
cause  the  death  of  many  birds,  which  would  eat  the  poisoned  worms, 
and  in  this  way  much  more  damage  be  done  to  the  country  at  large 
than  benefit. 

Besides,  there  are  many  useful  insects,  the  natural  enemies  of 
the  caterpillar,  which  might  be  thus  destroyed.  Among  those  are 
the  larvae  of  the  lady-bird,  the  ichneumon  flies,  and  many  others, 
which  keep  the  noxious  insects  in  proper  bounds.  It  would  be 
proper  for  agriculturists  to  study  well  the  natural  history  of  the 
insects  themselves,  and  the  potency  of  the  agencies  used  for  their 
destruction,  before  they  enter  upon  such  wholesale  destruction. 

15.  Bust  in  Cotton. 

Rust  in  cotton  is  a  vague  term,  and  is  generally  a  misnomer. 
There  is  a  genuine  rust  mentioned  by  some  writers,  occurring  mostly 
in  the  Gulf  States,  which  results  from  fungi  like  that  of  wheat.  It 
begins  and  spreads  from  a  common  centre,  as  the  microscopic  spores 
are  carried  by  the  breezes  from  one  stalk  to  another. 

Another  species  of  rust  is  generally  confined  to  small  patches, 
and  is  apt  to  occur  on  the  same  spots  of  land  for  successive  years. 
This  has  given  rise  to  an  idea  that  there  is  some  deficiency  in 


APPENDIX. 


373 


the  land  itself,  either  physical  or  chemical,  which  is  doubtless 
true. 

This  kind  of  rust  is  generally  more  fatal  to  the  crop  than  any 
other,  as  it  begins  early,  before  the  fruit  is  developed,  and  the  leaves 
often  assume  a  black  color,  owing  no  doubt  to  their  being  immature  ; 
hence  it  has  been  termed  black  rust,  as  contradistinguished  from  that 
which  seems  to  be  simply  a  premature  ripening  of  the  fruit  and  ex- 
haustion of  the  plant.  This  is  called  red  rust,  as  the  leaves  are 
reddish  brown,  and  present  the  exact  appearance  of  autumnal  decay. 

The  Might  which  has  for  a  number  of  years  destroyed  so  many 
cotton  fields,  and  is  known  in  familiar  parlance  as  rust,  is  not  parasitic 
in  its  character,  but  simply  an  exhaustion  or  giving  way  of  the  life 
of  the  plant,  such  as  w^ould  result  from  taking  a  spade  and  cutting 
off  all  the  lateral  roots  by  which  it  receives  nutrition ;  or  as  happens 
in  autumn  when  the  fruit  is  mature.  It  occurs  at  the  stage  of  fruit- 
ing, and  might  be  well  distinguished  from  all  others  fruit  rust  or 
plant  exhaustion. 

16.  Causes  of  Rust  in  Cotton. 
Many  theories  have  been  advanced  as  to  the  causes  of  rust  in  cot- 
ton. Some  have  gone  so  far  into  the  region  of  fancy  as  to  contend 
that  briers  and  poke-weed  in  the  neighborhood  of  cotton  fields  are  a 
prolific  source  of  the  fungi  which  generate  the  disease  in  the  cotton 
plant.  And  yet  possibly  this  might  be  true  of  a  genuine  parasitic 
rust,  which  we  believe  rarely  occurs  in  the  middle  and  northern  cot- 
ton belt. 

Although  originating  from  several  remote  causes,  the  different 
kinds  of  rust  have  but  one  proximate  cause,  viz.  deficient  nutrition. 
This  may  result  in  several  ways :  1.  From  the  abstraction  by  para- 
sitic growths  of  nutritive  juices  of  the  plant,  as  in  the  case  of  wheat. 
2.  From  the  sudden  giving  out  of  one  important  element  in  the  soil 
or  in  the  fertilizer  used,  especially  on  a  poor  soil.  3.  From  the  fail- 
ure of  a  supply  of  nutrition  because  of  drought.  There  may  exist 
plenty  of  soluble  matters  in  the  soil,  but  as  they  can  be  taken  up 
only  when  in  solution,  the  supply  fails  because  the  menstruum, 
water,  by  which  it  is  held  in  solution,  fails.  4.  From  too  much  water 
in  a  soil  from  any  cause,  as  above  noticed,  the  roots  become  un- 
healthy and  incapable  of  taking  up  nutrition.  5.  From  the  presence 
in  the  soil  of  a  corrosive  acid,  or  poisonous  principle,  which  destroys 
the  vitality  of  the  roots.  6.  From  a  hard,  impermeable  subsoil,  cans- 
ing  the  water  to  stand  around  the  roots,  and  thus  obstruct  nutrition, 


374 


APPENDIX. 


We  have  observed  blight,  or  premature  decay,  resulting  from  all 
of  these  causes,  especially  from  the  failure  of  water  to  supply  the 
accustomed  juices  requisite  to  sustain  the  life  of  the  plants.  Par- 
ticularly is  this  true  when  plants  have  been  supplied  with  a  full 
quota  of  all  the  elements  of  food,  by  concentrated  fertilizers,  and 
an  abundance  of  water.  The  force  of  absorption  under  such  circum- 
stances tends  to  enlarge  the  cells  and  expand  the  roots. 

This  has  been  well  established  by  Ritthausen,  who  produced 
two  crops  of  clover  in  1854,  one  manured,  the  other  not.  The  for- 
mer was  much  the  largest  in  bulk,  and  of  course  the  tubes  were  larger 
and  conveyed  more  of  the  juices  to  the  leaves  and  other  parts  of 
the  plant.  The  latter  was  more  compact,  with  smaller  tubes,  etc. 
It  was  a  very  wet  summer.  The  manured  plot  weighed,  when  fresh, 
22,256  lbs. ;  the  unmanured  18.815.  When  air-dried,  the  manured 
plot  had  lost  17,456  lbs.  of  water,  the  other  only  13,625,  making  the 
compact  unmanured  clover  to  excel  the  other  in  dry  hay,  390  pounds. 

Thus,  when  a  cotton  plant  has  been  highly  fertilized,  having 
an  abundant  supply  of  rain-water  to  convey  its  soluble  food  to  the 
plant,  the  du€ts  and  cells  are  all  the  time  full  and  distended 
with  the  juices  taken  up  by  the  absorptive  power  of  the  roots. 
Just  at  this  juncture  a  drought  sets  in,  the  supply  of  water  fails, 
and  premature  exhaustion  is  the  result. 

It  has  been  demonstrated  by  Hellriegel  and  others,  that  as  soon 
as  a  plant  begins  to  wilt,  it  is  evidence  of  the  fact  that  more  water 
is  exhaled  by  the  leaves  than  is  taken  up  by  the  roots.  The  fail- 
ure of  the  water  involves  a  failure  of  nutrition  to  the  plant,  hence  it 
begins  to  wilt,  turns  yellow,  and  gives  evidence  of  a  premature 
decay,  which  results  in  the  death  of  the  leaves,  and  the  drying  up 
of  the  plant.  The  farmer  announces  at  once  that  his  cotton  has 
rusted. 

17.  Effect  of  Fruitage. 

Another  thing  which  hastens  this  state  of  things  is  the  fruiting 
of  the  plant ;  which  makes  a  much  heavier  draught  for  nutritious 
food,  and  consequently  for  the  water  to  convey  it.  Hence  when 
cotton  has  been  highly  fertilized,  and  supplied  with  abundant  mois- 
ture, the  plant  in  a  succulent  growing  condition,  every  part  replete 
with  soluble  food,  and  the  fruit  in  the  process  of  formation,  a  sud- 
den cutting  otF  of  the  supplies  produces  exhaustion,  decay,  and 
death ;  while  in  rows  unfertilized,  and  not  advanced  far  enough  to 
have  much  fruit,  as  we  have  often  seen,  there  is  not  the  slightest 


APPENDIX. 


375 


tendency  to  this  state  of  things  ;  because  it  does  not  require  as 
much  moisture  or  nutriment,  the  tubes  and  cells  being  smaller  and 
easier  repieted,  the  soil  supply  of  nutrition  more  equable,  and  the 
plant  requiring  less,  having  not  yet  reached  the  point  of  fruitage, 
which  is  always  accelerated  by  manure.  The  exhalation  from  ferti- 
lized plants  is  also  much  greater,  as  the  leaves  are  more  numerous 
and  larger. 

Now  if  this  was  a  disease  dependent  on  fungi,  or  any  conta- 
gious or  epidemical  influence,  the  non-fertilized  rows  would  not  be 
spared,  as  is  uniformly  the  case.  If,  however,  the  drought  con- 
tinues long  enough,  the  fruitage  sets  in,  and  the  supply  of  water 
becoming  exhausted  in  the  unfertilized  soil,  the  same  results  take 
place  in  the  same  way,  though  in  a  more  modified  form. 

The  above  facts  have  been  demonstrated  again  and  again  by  the 
author.  At  present  (September,  1874),  at  this  experimental  station, 
we  have  a  plot  on  which  one  thousand  pounds  of  a  high-graded  am- 
moniated  superphosphate  was  put  per  acre.  The  fruit  has  matured 
rapidly,  and  is  mostly  open  ;  the  leaves  are  red,  and  many  of  them 
falling  off ;  it  is,  in  common  parlance,  Jjadly  rusted. 

Other  plots  with  only  200  pounds  of  fertilizer  per  acre,  have 
about  finished  fruiting,  and  are  passing  into  the  sere  leaf.  While 
those  which  have  no  manure  are  still  green,  having  fruit,  though 
sparse,  in  every  stage  of  development,  from  the  young  form  and 
the  open  blossom,  to  the  full-grown  boll. 

18.  Organic  Mattel'  a  Preventive  of  Bust. 
One  other  circumstance  indicates  the  true  origin  of  this  blight. 
Wherever  there  is  plenty  of  organic  matter  (humus)  in  the  soil, 
this  premature  decay  rarely,  if  ever,  takes  place.  It  begins  uni- 
formly in  the  poorest  spots  of  the  poorest  fields,  on  the  knolls, 
extending  down  the  sides  of  hills,  until  it  reaches  the  edge  of  the 
bottoms,  where  there  is  more  organic  matter  and  more  moisture. 
In  the  same  way,  and  for  the  same  cause,  new  grounds  recently 
cleared  and  put  under  cultivation,  seldom  show  symptoms  of  this 
blight. 

An  interesting  question  arises,  how  does  humus  act  as  a  preven- 
tive of  rust  ?  We  answer,  in  three  ways.  First,  by  increasing  the 
moisture  of  the  soil,  as  it  renders  it  more  porous,  more  permeable 
to  rains  and  dews,  and  more  accessible  to  capillary  waters  ;  while  it 
imbibes  more  moisture  from  the  air.    Schubler  demonstrated  that 


376 


APPENDIX. 


humus  will  absorb  five  times  more  moisture  from  the  atmosphere, 
than  common  ploughed  land.  Second,  by  furnishing  ammonia  to 
plants,  which  it  absorbs  and  holds,  as  well  as  the  inherent  nitrogen 
which  exists  in  all  organic  matter,  before  decomposition  takes  place. 
Third,  by  the  mineral  elements  associated  with  humus,  always 
held  in  soluble  proportions,  as  established  by  M.  Grandeau's  experi- 
ments in  France.  Whenever  there  is  humus  (hydro-carbon)  in  a 
soil,  there  must  be  the  mineral  elements  which  result  from  the 
same  source  of  the  humus,  viz.  decay  of  vegetable  matter.  Hence 
humus  in  its  widest  sense  is  a  preventive  of  plant  exhaustion, 
because  it  furnishes  an  equable  supply  of  moisture  and  nutrition. 

The  best  preventive  then,  for  this  plant  exhaustion,  or  rust  as  it 
is  called,  is  to  keep  the  land  well  supplied  with  vegetable  matter, 
which  is  so  rapidly  destroyed  under  the  exclusive  culture  of  cotton. 
A  proper  rotation  of  crops,  especially  the  interchange  of  small 
grain  every  three  or  four  years  at  most,  or  an  occasional  year's  rest,  or 
lying  fallow,  which  amounts  to  the  same,  with  the  judicious  applica- 
tion of  fertilizers,  will,  we  are  well  satisfied,  prevent  any  recurrence 
of  this  disease. 


II. 

INDIAN  COEN,  MAIZE. 

ZEA  MAYS. 
1.  Its  History  and  Belations  to  ClimMe. 

Indian  Corn  is  the  most  valuable  of  all  the  agricultural  plants 
of  this  country.  It  belongs  to  the  family  of  the  grasses  (Graminea). 
It  is  a  native  of  America,  and  was  found  in  a  state  of  cultivation  in 
every  place  in  the  new  world,  where  the  first  navigators  landed. 
Hence  it  was  named  from  the  aborigines  of  the  country. 

Maize  may  be  cultivated  successfully  between  the  40th  degree  of 
south  latitude  and  the  same  degree  north,  if  we  except  the  summits 
of  high  mountains,  and  perhaps  some  portions  of  the  torrid  zone  ; 
where  it  is  rather  a  chaffy  product,  and  very  much  damaged  by 
insects,  before  and  after  being  gathered.  Diminutive  varieties, 
which  ripen  in  a  short  time,  are  cultivated  in  the  most  northern 
counties  of  the  United  States,  as  high  as  4:1°  north  latitude. 


APPEXDIX. 


377 


2.  Its  Reproductice  Organs. 

This  remarkable  plant  is  peculiar  in  its  reproductive  organs, 
having  the  flower  separated  into  two  parts  ;  the  tassel  which  occu- 
pies the  summit  of  the  stalk,  representing  the  staminate  or  male 
flower,  and  the  silk  which  occupies  an  intermediate  position  below 
the  tassel,  representing  the  pistillate  or  female  flower. 

Nature  seems  to  have  fixed  these  relative  positions  in  order  that 
the  pollen  might  fall  upon  the  silk,  and  thus  make  it  fruitful.  In 
isolated  stalks,  however,  the  silk  receives  so  little  of  the  pollen 
from  its  own  tassel  as  to  bring  but  few  grains  to  perfection  ;  hence, 
the  necessity  of  having  a  number  of  stalks  near  by  or  in  the  same 
field  in  order  that  perfect  ears  and  a  full  crop  may  be  made. 

3.  Its  Habitudes. 

The  roots  of  maize  put  forth  and  grow  an  inch  or  two  before  the 
plumule  appears,  and  progress  so  very  rapidly  in  loose  soils,  as  ob- 
served by  Mr.  Lorain,  that  they  will  measure  12  inches  in  length 
when  the  stem  is  not  more  than  three  inches  high.  The  cotyledons 
expand  into  leaves  soon  after  they  break  the  soil,  and  other  leaves 
unfurl  in  succession  from  the  crown  of  the  plant,  until  the  tassel 
appears  wrapped  up  in  the  last  or  top  leaves.  The  leaves  increase 
in  length  and  width  from  the  ground  up  to  the  ear,  and  then  grad- 
ually diminish  till  the  last  top-leaves,  which  are  very  short  and 
narrow. 

The  brace  roots  of  Indian  corn  subserve  a  good  purpose,  as  a 
support  to  the  stalk  after  the  tassel  makes  its  appearance,  and  the 
ear  begins  to  form,  which  from  their  weight,  but  for  these  roots, 
would  pull  the  stalk  to  the  ground.  Farmers  sometimes  indis- 
creetly break  these  roots  with  the  hoe,  by  hilling  the  corn,  which 
makes  them  bleed,  and  requires  new  roots  to  be  formed,  thus  mak- 
ing a  heavy  draught  on  the  juices  of  the  plant  at  a  most  important 
time. 

4  4..   Varieties  of  Corn. 

There  are  quite  a  number  of  varieties,  or  sub-varieties ;  the 
most  distinct  of  which  are  the  white  flint,  the  yellow^  flint,  the 
gourd  seed,  the  Guinea  or  pop-corn,  and  the  sugar  corn.  Of  these, 
the  gourd  seed  is  perhaps  the  best  for  the  Southern  States  for  gen- 
eral purposes,  as  it  is  the  most  prolific.    The  white  flint,  it  is 


378 


APPENDIX. 


thought,  makes  the  best  bread,  while  the  yellow  corn  is  the  most 
nutritive,  and  answers  best  for  stock. 

There  are  a] so  red,  blue,  and  purple  corns,  which  are  not  culti- 
vated as  field  crops,  as  they  are  mostly  diminutive,  and  are  planted 
as  novelties. 

The  long  summers  of  the  South  tend  to  less  production  than 
further  north,  owing  to  the  growth  of  the  stalks,  which  in  some 
instances  will  reach  18  feet  in  height.  While  the  northern  varie- 
ties are  much  smaller  and  more  productive.  For  the  same  reason 
it  can  be  planted  much  thicker  than  at  the  south,  where,  in  many 
localities,  of  a  dry  year,  and  on  thin  lands,  seven  feet  by  three  is 
considered  the  best  distance.  We  found  on  the  experimental  farm 
(1873),  that  five  feet  by  three  produced  more  than  any  other  dis- 
tance.   With  less  rain  different  results  might  be  obtained. 

5.  Culture  of  Corn. 

Having  ascertained  the  best  distance  to  plant  corn,  its  cultiva- 
tion does  not  require  much  skill  or  science.  Deep,  thorough  pre- 
paration, subsoiling,  if  possible,  good  manuring,  and  shallow  culture, 
constitute  the  most  accepted  methods.  But  as  corn  is  a  surface- 
feeder,  having  no  tap  root,  and  none  that  penetrates  very  deeply 
into  the  ground,  it  is  essential  always  to  plant  so  as  to  prevent  the 
evils  of  a  drought,  which  destroys  so  many  crops.  In  order  to  this, 
the  first  step  is  early  planting,  even  at  the  risk  of  having  it  cut  down 
by  the  frost,  as  thereby  it  is  made  before  the  hot  droughty  days  of 
July  and  August  set  in.  There  is  no  question  that  corn  planted 
early  will  require  less  rain,  and  as  a  general  rule  get  more  than  that 
planted  late. 

Subsoiling  is  very  important  in  corn  culture  ;  more  so,  even,  than 
for  cotton,  and  for  the  same  reasons.  The  corn  should  be  planted  in 
the  bottom  of  a  deep  shovel  furrow,  always  in  the  drill,  and  on  top 
of  the  manure,  which  should  be  scattered  in  the  furrow,  as  too  much 
concentration  of  nitrogenous  fertilizers  near  a  hill  of  corn  generates 
heat,  and,  of  course,  lessens  the  moisture.  Ammonia,  either  in 
stable  manure,  cotton  seed,  or  ammoniated  phosphates,  is  a  great 
fertilizer  for  corn  ;  but  it  should  be  put  deep  under  the  corn,  for 
the  reasons  above  given.  The  advantage  of  deep  planting  is,  that 
it  saves  the  necessity  of  hilling,  causes  the  principal  lateral  roots  to 
grow  deeper  in  the  ground,  where  there  is  more  moisture,  and 


APPENDIX. 


379 


enables  the  plough  to  cover  up  all  the  small  grass  around  the  corn, 
hy  which  much  labor  is  saved  in  hoeing. 

The  old  idea  of  ploughing  corn  deep  so  as  to  break  the  roots  and 
cause  more  to  spring  out,  and  thereby  multiply  the  feeders,  has  long 
since  been  exploded,  at  least  among  scientific  men.  True,  corn  has 
great  powers  of  recuperation,  and  with  plenty  of  rain  it  is  not  seri- 
ously damaged  by  deep  ploughing,  except  in  the  later  stages ;  but 
always  in  dry  weather  this  is  a  great  calamity,  after  the  roots  have 
spread  to  any  great  extent.  The  ground  should  be  stirred  often,  but 
never  deeper  than  a  common  sweep  will  enter,after  the  first  plough- 
ing, near  the  corn.  The  centre  of  the  rows  may  be  ploughed  as 
deep  as  you  please,  until  the  last  ploughing,  when  it  should  be 
shallow  also. 

6.   Value  and  Uses  of  Indian  Corn. 

The  grain  of  maize  is  on  many  accounts  the  most  valuable  cereal 
in  the  country.  It  not  only  furnishes  the  principal  food  for  the 
horses,  mules,  and  work -oxen  of  the  whole  country,  but  is  the  prime 
article  for  fattening  pork  and  feeding  milch  cows.  It  also  mainly  fur- 
nishes the  laboring  classes  of  the  South  and  West  with  bread,  being 
not  only  cheap  but  nutritive  and  wholesome,  while  the  better  classes 
make  of  it  many  dainty  dishes,  and  as  a  vegetable  it  is  used  as 
green  corn  perhaps  more  universally  than  any  other  article. 

There  is  no  part  of  this  plant  which  does  not  subserve  some 
valuable  end.  The  stalk  itself  is  a  valuable  manure,  either  by  being 
turned  under  with  the  plough  for  a  succeeding  crop,  or  cut  and 
hauled  as  rough  forage  and  litter  for  the  cattle  stalls. 

The  shucks  or  husks  make  an  excellent  forage  for  oxen  and  dry 
cattle  during  the  winter,  and  mules  will  feed  upon  them  at  night, 
during  plough  time,  with  much  advantage.  The  blade  makes  a 
healthy  provender  for  the  more  delicate  stomach  of  the  horse  ;  while 
the  cobs,  after  the  grain  has  been  shelled  off,  make  good  fuel,  and 
their  ashes  contain  a  high  per  cent,  of  potash  for  fertilizing  or  other 
purposes. 

7.  A  nalyses  of  Indian  Corn  contrasted  with  other  Grain. 

We  present  a  table,  taken  from  all  the  reliable  analyses  of  cereal 
grains,  as  compiled  by  Wolff  and  Knopp,  in  which  the  proximate 
principles  of  maize  are  shown,  as  well  £^s  cojitrasted  very  favorably 
with  those  of  other  grains. 


380 


APPENDIX. 


Table  showing  the  proximate  analyses  of  agricultural  grains 
with  amount  of  digestible  food. 


Albuminoids. 

Carbo- 

Fat. 

Crude  fibre. 

Digestible 
matters. 

Water. 

Rice  

.  7.5... 

...76.5... 

...O.5.. 

....  0.9... 

...84.5... 

...14.6 

Wheat. . . 

.18.0... 

...67.6... 

...1  5.. 

....  3.0... 

..82.1... 

...14.4 

Rye  

.11.0... 

,..69.2... 

...2.O.. 

....  3.5... 

...82.2... 

...14.3 

Barley. . . 

.  9.0... 

...65.9... 

...2.5.. 

....  8.5... 

...77.4... 

...14.3 

Oats  

.12.0... 

...60.9... 

...6.O.. 

....10.3... 

...78.9... 

...14.3 

Ind.  Corn 

.10.0... 

..68.0... 

...7.O.. 

....  5.5... 

...85.0... 

..14.4 

Peas  

.22.4... 

..52.3... 

...2.5.. 

....  9.2... 

...78.2... 

.  .14.3 

This  table  shows  that  while  rice  has  less  crude  fibre  than  any 
of  the  other  grains,  maize  has  a  greater  per  cent,  of  digestible  sub- 
stances ;  and  although  peas  have  more  of  the  albuminoids,  which 
constitute  the  richest  food,  yet  the  corn  has  more  sugar,  and  starch, 
and  cellulose,  as  well  as  more  fat. 

From  the  same  source,  as  above,  {vide  Table  in  Appendix  to  How 
Crops  Grow),  the  per  cent,  of  ash  in  the  grain  of  maize  is  shown 
to  be  12.3  ;  of  which  there  is 


Potash  3.3 

Soda  0.2 

Magnesia  1.8 

Lime  0.3 

Phosphoric  acid  5.5 

Sulphuric  acid  0.1 

Silica  0.3 

Sulphur..  1.2 


8.  Depredations  of  Birds  o/nd  Insects. 

The  Indian  corn  has  many  enemies,  but  none  of  them  very  disas- 
trous. Perhaps  the  birds  do  more  damage  than  any  of  them.  Among 
these  the  crow  and  the  blackbird  stand  preeminent.  The  scare-crow, 
strychnine,  and  shot-gun,  have  all  been  used  with  but  little  effect. 
Giving  the  seed  a  coating  of  soft  tar  has  proved  successful  in  some 
cases.  But  the  most  humane,  and  the  safest  and  most  effectual 
remedy,  is  to  plant  the  corn  thick,  four  or  five  seeds  in  the  hill. 
This  will  allow  some  for  the  birds,  the  moles,  and  the  cut- worms, 
and  generally  leave  enough  for  a  good  stand. 


APPENDIX. 


S81 


Some  farmers  feed  their  birds  while  their  corn  is  in  danger  from 
them,  which  is  only  a  week  or  two,  particularly  on  the  swamps 
where  they  frequent,  and  doubtless  iliej  have  received  pay  with 
heavy  interest,  not  only  in  the  good  stand  of  corn,  but  the  destruc- 
tion by  them  of  the  cotton  caterpillar  and  other  insects  which 
damage  crops.  Planters  have  observed  that  caterpillars  destroy  but 
little  cotton  near  swamps  inhabited  by  birds. 

The  cut-wornij  belonging  to  the  Agrotidide,  is  a  depredator  on 
young  corn,  and  is  said  to  be  very  destructive  in  the  Northern 
States.  They  have  already  been  described  under  the  insects  hurtful 
to  cotton.  We  have  never  seen  any  very  extensive  damage  done  by 
them  in  the  South.    They  infest  stubble  lands  especially. 

A  smaller  species,  called  the  bud-wor7n,  is  more  disastrous.  It 
nestles  in  the  bud  of  the  young  plant,  and  eats  it  out  so  completely 
as  to  destroy  its  vitality.  It  operates  mostly  in  low  places  where 
the  land  is  more  peaty  and  moist,  and  frequently  ruins  the  stand 
of  corn.    The  remedy  is  thick  planting  in  all  such  localities. 

0.  Diseases  of  Indian  Corn. 

Indian  corn  is  sometimes,  but  rarely,  subject  to  a  species  of  rust 
on  the  leaves,  which  is  evidently  a  microscopic  fungi.  But  we  have 
never  seen  any  extensive  damage  from  it. 

In  low,  flat  lands,  corn  has  what  farmers  term,  the  yellows,  which 
is  produced  during  wet  springs  by  the  rising  of  bottom  waters  in  the 
soil,  and  the  consequent  imperfect  supply  of  nutrition.  If  it  con- 
tinues any  length  of  time,  the  stalk  ceases  to  grow,  and  becomes 
hard  and  incapable  of  conveying  but  a  small  amount  of  nutritive 
juices  to  the  ear,  so  that  the  crop  is  ruined  or  seriously  damaged, 
despite  the  return  of  dry,  warm  weather,  and  the  sinking  of  the 
water.  Under-draining  is  a  very  effective,  but  rather  expensive 
remedy  for  such  lands. 

Where  this  is  impracticable,  the  corn  beds  should  be  thrown  up 
as  high  as  possible,  and  the  rows  run  in  a  direction  to  drain  off  the 
rain  water  by  the  middle  furrows. 

10.  The  Black  Blast,  or  Corn  Fungus 

black  blast,  SL  fungus  growth  which  destroys  the  ear,  is  a 
common  disease,  and  some  years  injures  the  crop  very  considerably. 
Some  have  supposed  it  to  originate  in  wounds  inflicted  on  the  young 
stalk  by  the  hoe,  or  plough.    This  theory,  however,  will  not  account 


382 


APPENDIX. 


for  the  disease,  as,  with  few  exceptions,  it  always  occurs  in  the  husk 
which  is  not  damaged  itself.  In  some  cases  there  is  only  a  partial 
injury  to  the  ear' a  portion  of  the  cob  and  grains  being  healthy, 
and  occasionally  only  a  few  small  fungi,  which  feed  upon  and  de- 
stroy the  adjacent  grains.  It  is  evidently  a  parasite,  being  propa- 
gated by  spores,  and  feeding  on  the  juices  of  the  stalk,  which  were 
intended  for  the  grains.  It  prevails  most  extensively  of  wet  sum- 
mers, when  the  corn  grows  rapidly  and  luxuriantly,  and  is  found 
more  frequently  on  rich  lands  than  poor. 

One  remarkable  fact,  which  shows  well  the  paternity  of  this 
fungus  is,  that  the  longer  corn  is  planted  in  the  same  field  the  more 
it  prevails.  This  is  traditional  with  old  farmers,  and  was  confirmed 
in  many  instances  during  the  Confederate  war  by  observing  men 
when  there  was  no  rotation  with  cotton.  We  planted  ourselves  a 
fresh  field  with  rich  native  soil  four  successive  years,  and  the  last 
year  the  crop  was  more  infested  with  this  stinking  blast,  than  any 
we  had  ever  seen.  At  first  it  was  supposed  to  originate  from  some 
chemical  deficiency  in  the  soil,  owing  to  repeated  croppings  of  the 
same  cereal ;  but  it  is  very  clear  that  the  spores  by  which  this 
fungus  propagates  itself  are  increased  annually,  upon  the  principle 
that  where  there  are  more  plants  there  will  be  more  seed ;  and  the 
intervention  of  one  year  in  cotton  or  something  else,  will  destroy 
many  of  the  spores,  and  cause  a  decrease  of  the  disease  the  succeeding 
year. 

III. 

WHEAT. 

TEITICUM  VULGAEE. 

1.  Its  History  and  Botanical  Relations. 

This  important  cereal  derives  its  name  from  the  ancient  mode  of 
preparing  the  flour.  Triticum  being  derived  from  the  Latin  tritus, 
rubbing  or  grinding,  as  between  two  stones. 

Wheat  is  the  most  nutritious  and  universally  distributed  food 
of  man,  as  well  as  the  most  ancient.  The  corn  of  the  Jews,  and 
of  the  Egyptians  before  them,  was  a  species  of  triticum,  from  which 
many  and  important  varieties  have  sprung.    It  is  believed  to  have 


APPENDIX. 


383 


been  coeval  with  the  creation,  as  implied  in  the  curse,  "  In  the  sweat 
of  thy  face  shalt  thou  eat  bread." 

Botanists  describe  the  calyx  of  wheat  as  consisting  of  two  valves 
or  glumes  (husks),  enclosing  several  florets  or  diminutive  flowers. 
In  each  of  these  there  are  two  valves  forming  the  corolla,  and  en- 
closing the  grain,  which  is  free. 

2.   Varieties  and  Soils. 

Linnaeus  mentioned  six  species  of  wheat  in  his  day.  Botanists 
now  enumerate  over  thirty,  embracing  several  hundred  sub-varieties. 
For  all  practical  purposes  these  varieties  might  be  embraced  under 
a  few  simple  terms,  as  red  and  white  wheat,  indicating  the  different 
kinds  of  flour  ;  or  winter  and  spring  wheat  showing  the  varieties 
as  adapted  to  seasons.  There  are  also  species  of  bearded  wheat, 
having  long  spikelets,  as  distinguished  from  those  which  are 
smooth. 

There  is  great  difference  in  many  varieties  of  wheat ;  some  of 
them  being  more  nutritious  than  others,  some  being  less  subject  to 
rust  and  other  diseases,  and  some  growing  more  luxuriantly  on 
poor  land  than  others.  As  a  general  rule,  however,  those  which 
do  not  thrive  well  on  thin  land,  make  up  for  their  lack  in  weight, 
in  having  a  greater  percentage  of  gluten,  or  nitrogenous  matter. 

Common  varieties  may  be  greatly  improved  by  the  selection  of 
seed  every  year,  sowing  at  tlie  right  season,  and  on  the  right  kind  of 
soil. 

Some  varieties  will  branch  much  more  than  others,  and  thus 
have  more  heads  and  bear  more  grain.  This  is  termed  tillering, 
and  is  a  very  important  quality  to  be  noticed  in  the  selection  of 
good  wheat.  The  number  of  grains  in  the  head,  as  well  as  the 
character  of  the  grains,  is  also  quite  essential  in  determining  a  good 
variety. 

Soil  has  much  to  do  with  the  character  of  wheat,  as  well  as  the 
amount  produced.  A  white  variety  sown  upon  red  land  will  in  a 
few  years  be  changed  into  red  wheat. 

Clay  lands  are  much  better  for  wheat  than  sandy  soils,  growing 
out  of  their  physical  advantages  (compactness)  as  well  as  their 
chemical  qualities,  generally  having  more  potash  and  other  mineral 
food,  as  well  as  retaining  more  ammonia,  which  is  a  most  essential 
salt  in  the  production  of  vigorous  wheat. 


384 


APPENDIX. 


3.  Selection  and  Preparation  of  Seed  Wheat. 

The  best  method  for  selecting  seed  wheat  is  to  pour  it  from  a 
height  on  a  windy  day.  Those  grains  which  are  the  ripest  and 
heaviest  will  fall  directly  under  the  hand,  from  which  the  seed 
should  always  be  selected.  This  process,  followed  up  annually, 
would  insure  freedom  from  smi/^,and  other  diseases  dependent  to  a 
large  extent  on  faulty,  immature  grains. 

There  is  much  advantage  also,  in  southern  latitudes,  where  wheat 
is  not  exactly  indigenous,  to  obtain  seed  from  further  north. 

Before  sowing,  the  seed  should  be  steeped  in  a  strong  brine  for 
five  minutes.  The  faulty  grains,  if  any,  rising  to  the  surface,  should 
be  skimmed  off ;  and  if  the  wheat  be  smutty  the  washing  should  be 
repeated  in  a  solution  of  bluestone  (one-fourth  of  a  pound  to  a 
bushel  of  wheat),  to  stand  for  twelve  hours.  One-twelfth  its  bulk 
of  fresh  pulverized  quick  lime  should  now  be  added  previous  to 
sowing.  (Allen.) 

Still  a  better  method  of  selecting  wheat  seed,  as  proven  by  recent 
experiments  in  England,  might  be  adopted,  by  which  all  of  the 
trouble  of  the  above  modes  would  be  obviated.  Select  by  hand 
each  year  a  number  of  the  most  perfect  grains  from  the  best  stalks, 
and  plant  in  a  plot  of  rich,  healthy,  well-drained  wheat  soil,  one 
grain  in  the  hill,  giving  good  distance.  The  land  should  be  of  good 
tilth  and  well  cultivated.  These  experiments  show  that  the  more 
grains  sown  the  fewer  the  number  of  ears  to  each  acre,  and  vice 
versa.  By  this  method,  in  a  few  years,  a  farmer  might  greatly 
improve  his  variety  of  wheat,  and  have  enough  seed  for  his  whole 
crop. 

4.  Drilling  Wheat. 

Most  farmers  are  well  apprised  of  the  importance  of  drilling 
wheat ;  but  on  account  of  the  extra  time  for  preparing  the  land,  and 
the  extra  labor  of  sowing,  they  generally  adopt  the  old  mode  of 
broadcasting.  In  order  to  meet  this  objection,  we  adopted  a  plan  in 
the  autumn  of  1873,  by  which  wheat  may  be  effectually  drilled, 
without  a  machine,  and  by  the  usual  mode  of  broadcast  sowing 
with  exactly  the  same  amount  of  ploughing. 

On  the  first  of  November  we  ridged  up  a  plot  of  ground  with  a 
scooter  plough,  i.e.  we  ran  the  furrows  about  seventeen  inches 
apart,  which  threw  up  the  ground  in  sharp  ridges  or  lists.    On  this 


ArrEXDix. 


385 


we  sowed  Tappalianiiock  wheat  at  the  rate  of  two  pecks  to  the  acre. 
It  was  covered  by  bursting  open  these  ridges,  which  required  just 
as  many  furrows  for  broadcast  sowing. 

The  only  additional  labor  used  on  the  drilled  wheat  was  one  fur- 
row run  between  the  rows  during  the  month  of  March,  when  in  the 
joint,  with  a  subsoil  plough.  The  helve  of  this  plough  being  a  bar 
of  iron,  threw  up  no  dirt  on  the  wheat,  but  answered  the  double 
purpose  of  draining  the  land  and  opening  it,  that  the  atmosphere 
might  penetrate,  and  thus  prepare  additional  food  for  the  plant. 
The  good  effect  was  very  perceptible. 

We  sowed  another  plot  by  its  side  of  the  same  size  and  fertility, 
with  double  the  amount  of  seed.  The  drilled  wheat  grew  off  faster, 
and  was  some  sis  inches  taller,  with  much  heavier  heads  than  the 
broadcast.  Another  plot  was  fertilized  with  300  pounds  per  acre  of 
.ammoniated  superphosphate. 

The  broadcast  plot  made  at  the  rate  of  414  pounds  of  grain  per 
acre  (G.09  bushels),  the  straw  weighing  8363^  pounds;  that  sown  in 
the  drill  made  o^7^  pounds  of  grain  (8.62  bushelg)  and  812  pounds 
of  straw. 

By  this  simple  plan,  in  a  field  of  ten  acres,  we  would  have  saved 
five  bushels  of  seed  wheat,  allowing  one  bushel  for  the  broadcast 
and  half  a  bushel  for  the  drilled,  and  have  made  2Q}4  bushels  more. 

The  fertilized  plot  produced  12.07  bushels  of  grain,  equal  to 
724^^  pounds,  and  979  pounds  of  straw  per  acre. 

Our  impression  is  that  one  peck  of  seed  thus  sown  will  do  as 
w^ell  as  a  larger  amount,  particularly  if  a  roller  is  used  to  make  the 
ground  more  compact,  and  bring  the  w^ieat  falling  into  the  bottom 
of  the  furrows  nearer  the  surface. 

In  the  estimate  of  profit  and  loss  in  this  experiment,  we  should 
take  into  the  account  the  exhaustion  of  the  soil  of  the  mineral 
food.  Thus,  in  contrasting  the  first  and  second  plots,  while  the 
drilled  wheat  made  lOoJ^  pounds  more  of  grain  than  the  broadcast, 
it  actually  took  off  243>2  pounds  more  of  straw.  Then  for  every 
bushel  of  grain  made  on  the  broadcast  system,  there  is  carried  off 
137  pounds  of  wheat  straw,  while  for  the  same  amount  of  grain 
w^hen  drilled,  there  is  carried  off  99  pounds  of  straw.  This,  then, 
involves  considerably  more  labor  in  cutting,  reaping,  hauling,  and 
thrashing  for  the  amount  of  grain  obtained  ;  and  takes  off  about  35 
per  cent,  more  of  all  the  valuable  substances  making  up  agricultu- 
ral plants. 

17 


386 


APPENDIX. 


Eecent  experiments  in  England  show  that  thin  sowing  ol  wneat 
in  drills  is  much  more  productive  than  thick  sowing.  By  special 
culture  on  small  plots,  having  one  grain  in  the  hill,  a  crop  at  the 
rate  of  108  bushels  per  acre  has  been  produced,  and  another  of  162 
bushels. 

5.  Fertilizers  for  Wheat. 

While  ammonia  is  an  essential  fertilizer  for  wheat,  yet  it  has  to 
be  used  judiciously,  as  too  much  of  it,  especially  on  poor  land,  will 
produce  much  straw  at  the  expense  of  the  grain.  Hence  stable 
manure,  cotton  seed,  and  Peruvian  guano  should  be  used  sparingly, 
and  in  conjunction  with  lime,  ashes,  superphosphate,  potash,  and 
other  mineral  fertilizers. 

Lime  acts  well  on  wheat,  not  only  as  food,  but  as  a  solvent, 
developing  the  inert  nitrogen  of  the  organic  matter  into  ammonia, 
as  well  as  eliminating  silica  from  its  insoluble  combinations,  and 
preparing  silicate  of  lime,  so  abundant  in  wheat  straw.  Thus, 
where  lime  is  deficient  and  other  fertilizers  are  abundant,  the  wheat 
lodges,  as  it  is  termed,  falling  from  weakness,  and  produces  but  little 
grain. 

Ashes  will  act  like  lime,  having  much  of  its  caustic  properties, 
and  possessing  as  it  does,  not  only  lime  and  silica  in  available  forms, 
but  other  essential  mineral  substances. 

6.  Chemical  Composition  of  Wheat. 

In  1,000  pounds  of  the  grain  of  wheat  air-dried  (Wolif  and  Knop), 
there  is  of  nitrogen  20.8  pounds,  and  of  ash  17.7  pounds;  of  which 


there  is  of 

Potassa.  5.5 

Soda  0.6 

Lime  0.6 

Magnesia  2.2 

Phosphoric  acid  8.2 

Sulphuric  acid  0.4 

Silicic  acid  0.3 

In  100  pounds  of  winter  wheat  there  was  2.0  of  ash,  14.4  of 
water,  and  83.6  of  organic  matter;  which  had  of 

Albuminoids  13.0 

Carbo-hydrates  67 . 6 

Crude  fibre   3.0 

Fat,  etc   1.5 


APPENDIX. 


387 


Wheat  grown  in  a  warm  climate  lias  more  nitrogen  (gluten), 
according  to  the  per  cent,  of  starch,  than  that  grown  in  a  cold  cli- 
mate. Hence  Georgia  wheat  commands  a  better  price  in  New  York 
tlian  northern  raised  wheat.  Starch  being  largely  composed  of 
carbon  and  oxygen,  is  a  generator  of  heat,  and  hence  food  of  this 
character  is  better  adapted  to  a  cold  climate. 

A  grain  of  wheat  cut  crosswise  will  show  the  outer  coat  com- 
posed of  cellular  tissue,  or  bran  ;  the  next  layer  to  this  is  the  gluten, 
and  the  central  portion  the  starch,  which  constitutes  the  largest  part 
of  the  kernel.  Much  of  the  gluten  (which  is  a  mixture  of  albumi- 
noids, with  a  little  starch  and  fat)  is  lost  by  the  process  of  grinding 
flour.  In  the  manufacture  of  a  barrel  of  flour,  sixty  to  seventy 
pounds  are  lost  with  the  bran,  when  there  should  be  only  about  ten 
pounds. 

The  plan  of  cutting  wheat  before  it  i«  fully  ripe,  while  it  whitens 
the  flour,  decreases  somewhat  the  quantity  and  deteriorates  the 
quality.  A  sample  of  Narbonne  wheat,  cut  eighteen  days  before 
being  fully  ripe,  had  only  six  per  cent,  of  gluten,  while  that  which 
remained  and  matured  had  tw^elve  per  cent. 

7.  Bust  in  Wheat,  Pnccinia  Graminas. 

As  early  as  1867,  Fontana  published  an  account  of  this  destructive 
pest :  and  since  then  botanists  have  pui'sued  the  investigation  with 
much  interest  and  assiduity.  It  is  i\ow  admitted  by  all  scientists  to 
be  a  microscopic  fungus,  to  which  the  name  of  Puccinia  graminas 
has  been  given.  It  attacks  both  stems  and  leaves  and  glumes  of 
all  kinds  of  grain,  having  at  first  an  orange  colored  appearance 
(resembling  rust  of  iron,  hence  the  common  name) ;  it  afterwards 
assumes  a  deep  chocolate  color. 

One  stoma  on  a  straw  will  produce  from  twenty  to  forty  fungi, 
and  each  of  them  it  is  believed  will  produce  at  least  one  hundred 
spores,  or  reproductive  particles,  so  that  the  progeny  of  a  single  stoma 
will  be  enough  to  infest  a  whole  plant. 

The  period  of  germination  is  supposed  to  be  about  one  w^eek. 
The  spores,  being  very  light,  are  wafted  about  in  the  air,  lighting 
upon  adjacent  stems,  and  will  germinate  under  the  influence  of 
warm,  damp  w^eather,  and  prove  more  or  less  destructive,  according 
to  the  favorableness  of  the  weather  for  their  increase  and  growth. 

Plants  have  pores  which  are  closed  in  dry  weather,  and  op*en  and 
expand  in  warm,  moist  weather.    It  is  supposed  that  these  pores  are 


388 


APPENDIX. 


thus  made  receptacles  of  the  spores  of  this  parasitic  fungus,  where 
they  immediately  take  root,  intercepting  the  nourishment  intended 
for  the  grain  ;  as  it  has  been  ascertained  by  analysis  that  these  fungi 
contain  very  much  the  same  constituents  as  the  flower. 

Some  kinds  of  wheat  are  more  affected  by  rust  than  others,  and  in 
northern  climates,  fall  wheat  suffers  more  than  that  sown  in  spring. 

Farmers  in  England  affirm  that  wheat  sown  in  the  neighborhood 
of  the  barberry  bush  seldom  escapes  the  blight,  as  it  is  supposed  that 
the  spores  are  generated  and  preserved  on  these  bushes. 

It  is  believed  that  the  spores  may  be  perpetuated  from  undecom- 
posed  straw  carried  out  into  the  fields  as  manure.  If  this  be  true, 
farmers  should  be  careful  in  this  matter,  as  well  as  in  destroying 
all  grasses,  in  fields  producing  rusted  wheat. 

8.  Smut,  Wheat  Fungus. 

The  smut  is  a  dark  brown  fungus,  which  takes  possession  of  the 
grain,  and  converts  all  of  the  nutritive  juices  into  a  most  offensive 
and  poisonous  substance. 

This  parasitic  fungus  is  undoubtedly  propagated  by  spores;  and 
when  wheat  once  becomes  infested  with  it,  it  is  difficult  to  extirpated- 
it.  It  seems  to  attack  the  weaker  grains  which  have  but  little  vital- 
ity and  power  of  resistance ;  hence  it  is  believed  that  a  very  effec- 
tive remedy  is  to  plant  only  the  perfect  sound  grains,  and  let  the 
others  be  separated  from  the  seed  by  methods  above  indicated. 

Bluestone  seems  to  be  the  effectual  remedy.  It  probably  acts  by 
killing  the  germ  in  all  the  faulty  grains,  which  possess  feeble 
vitality.  Salt  brine  acts  perhaps,  not  so  much  by  killing  the  germs, 
as  by  causing  more  of  the  weaker  grains  to  float  on  the  surface,  which 
can  be  skimmed  off  and  separated  from  the  healthy  seed. 

9.  Insects  Injurious  to  Wheat. 

These  are  very  numerous  ;  some  of  them  preying  upon  the  grow- 
ing plant,  others  sucking  out  the  juices  of  the  grain  before  its  ma- 
turity, and  others  preying  upon  the  matured  grain  after  it  is  housed. 

Among  those  which  we  cannot  describe  particularly  in  this  work, 
(but  are  fully  described  in  Harris's  Insects  Injurious  to  Vegetation), 
we  mention  the  Thrips  cerealium.  This  is  similar  to  the  small  white 
wo^^ii  found  in  wheat  (wheat  maggot).  It  is  supposed  to  suck  the 
juices  out  of  the  seed. 

Wheat  caterpillars,  probably  oflfspring  of  the  species  Noctua,  de- 


APPENDIX. 


3S9 


your  the  grains  of  wheat  while  growing  and  after  being  harvested. 
Another  species  of  worm  similar  to  those  of  Europe  which  are  the 
product  of  the  grain  moth  (Tinea  granella),  infest  granaries,  gnaw- 
ing the  ends  of  the  wheat  and  other  grains,  and  spinning  a  thin 
web  uniting  a  number  together,  and  thus  producing  considerable 
damage. 

The  joint  worm  (produced  from  a  moth  belonging  to  the  genus 
Eurytoma)  has  produced  considerable  damage  in  Virginia  and  other 
States.  They  infest  the  straw  of  wheat  and  barley,  sucking  its  juices 
and  cutting  ofif  the  supply  of  nutriment  to  the  grain. 

The  European  wheat  fly  (Cecidomyia  tritici),  a  very  small  gnat, 
produces  a  little  worm  which  preys  upon  the  pollen,  and  afterwards 
the  germ  of  the  fruit,  and  is  in  some  seas.ons  very  destructive  to  the 
wheat  crop.  A  similar  grain  worm  has  been  observed  for  several 
years  in  the  Northern  and  Eastern  States. 

10.  The  Chinch  Bug,  Lygoeus  Leucoptevus. 

This  insect  is  said  to  resemble  the  bed-bug,  both  in  color  and 
scent.  Its  eggs  are  laid  in  the  ground  where  its  young  have  been 
found  in  great  numbers,  at  the  depth  of  an  inch.  They  make  their 
appearance  early  in  the  summer,  but  some  of  them  continue  alive  in 
their  places  of  concealment  during  the  whole  winter. 

They  prevail  mostly  in  the  Western  States,  south  of  the  fortieth 
degree  of  latitude,  and  commit  extensive  depredations  on  the  corn 
and  wheat  fields.  They  travel  like  locusts  in  immense  columns 
from  field  to  field,  destroying  everything  before  them. 

They  make  their  appearance  on  wheat  about  the  middle  of  June, 
and  though  very  destructive  to  it,  are  by  no  means  confined  to  it  ; 
but  appear  in  their  various  stages  of  growth  on  all  kinds  of  grain, 
corn,  and  grass,  during  the  whole  summer.  (Flarris.) 

11.  Hessian  Fly,  Cecidomyia  Destructor. 

This  far-famed  insect  obtained  its  common  name  from  the  fact 
that  it  was  first  seen  in  the  wheat-fields  about  the  time  the  Hes- 
sians landed  in  this  country,  under  the  command  of  Sir  William 
Howe,  during  the  Revolutionary  War.  It  was  supposed  that  the 
straw  that  they  brought  with  them  was  infested  by  it.  Its  botanical 
name  was  given  by  Mr.  Say. 

Upon  subsequent  investigation  it  was  said  that  no  such  insect 
could  be  found  in  Germany  ;  but  one  answering  its  description,  and 


390 


APPENDIX. 


of  exactly  the  same  habits,  had  long  been  known  in  the  vicinity  of 
Geneva.  In  1833  the  wheat  crops  of  Austria  and  Hungary  were 
seriously  injured  by  an  insect  of  the  same  kind. 

From  the  point  of  Lord  Howe's  debarkation  on  Staten  and  Long 
Islands,  the  insect  seemed  to  spread  at  the  rate  of  about  thirty  miles 
a  year,  until  tlie  whole  country  had  been  infested  by  it.  Every 
species  of  small  grain,  and  even  timothy  grass  was  attacked  by 
them  ;  and  in  some  places  their  ravages  in  the  larva  state  were  so 
great  that  the  cultivation  of  wheat  had  to  be  abandoned. 

Mr.  Llarris,  in  his  book  on  Insects  Injurious  to  Vegetation,  thus 
describes  the  Hessian  fly.  The  head,  antennae,  and  thorax  are 
black.  The  hind  body  is  tawny,  more  or  less  widely  marked  with 
black  on  each  wing,  and  clothed  with  fine  grayish  hairs.  The  egg 
tube  of  the  female  is  rose  colored.  The  wings  are  blackish,  except 
at  the  base  ;  the  legs  pale  or  reddish,  and  the  feet  black." 

According  to  Mr.  Herrick  (who  has  studied  the  habits  of  this  in- 
sect) two  broods  are  brought  to  maturity  during  the  year,  one  in  the 
spring  and  the  other  in  the  autumn.  From  the  egg  to  the  winged 
state  they  live  about  one  year.  The  flies  lay  their  eggs  on  the 
young  plants  long  before  the  grain  is  ripe.  As  soon  as  the  wheat 
comes  up  in  the  fall,  and  begins  to  show  a  leaf  or  two,  the  flies  appear, 
pair  off*  and  begin  to  lay  their  eggs,  which  occupies  several  weeks. 
They  appear  as  minute  red  specks  in  the  longitudinal  cavities  of 
the  blades,  the  number  being  often  twenty  or  thirty  on  a  single 
leaf.  The  eggs  hatch  out  in  about  four  days,  producing  a  maggot 
of  a  pale  red  color. 

As  soon  as  hatched,  the  maggot  crawls  down  the  leaf,  till  it  comes 
to  a  joint  of  the  main  stalk  a  little  below  the  surface  of  the  ground* 
where  it  fixes  its  abode  with  its  head  toward  the  root  of  the  plant. 
Here  they  remain  till  all  their  metamorphoses  are  completed. 
They  do  not  penetrate  the  stalk,  nor  feed  upon  it,  but  are  nourished 
by  the  juices  of  the  plant,  which  they  appear  to  take  up  by  suction. 
One  maggot  could  not  destroy  a  single  plant,  but  when  several  are 
fixed  in  this  way  around  the  stem  it  is  impoverished,  becomes  weak- 
ened, and  withers  and  dies. 

These  insects  continue  to  increase  in  size,  and  obtain  their  full 
growth  in  five  or  six  weeks,  when  they  measure  three-twentieths  of 
an  inch  in  length.  After  lying  in  the  chrysalis  state  during  the 
winter,  when  the  weather  becomes  warm  in  the  spring,  in  April  or 
May,  according  to  the  climate,  they  emerge  from  their  winter  quar- 


APPENDIX. 


331 


ters  by  breaking  througli  one  end  of  their  shells,  being  now  trans- 
%     formed  into  files. 

Various  suggestions  have  been  made  to  prevent  the  ravages  of 
the  Hessian  fly,  as  the  selection  of  seed  wheat  from  localities  not 
infested  by  them,  soaking  it  in  strong  brine,  sowing  on  clean,  culti- 
vated lands,  etc.,  all  of  which  may  be  advantageous,  but  none  perhaps 
entirely  effectual.  A  most  efficient  remedy  has  been  found  in  the 
Southern  States,  adopted  years  ago,  which  seems  to  have  rid  the 
country  of  this  pest ;  we  know  not  how  it  will  apply  to  regions  fur- 
ther north.  It  was  found  that  the  fly  always  disappeared  after  the 
first  cold  spell,  having  destroyed  the  early  crops.  Farmers  at  once 
quit  sowing  what  are  called  late  varieties  of  wheat,  as  the  Big  White, 
Blue  Stem,  etc.,  and  sowed  early  varieties,  as  the  Little  White,  Medi- 
terranean, etc.,  which  would  produce  good  crops  by  sowing  in  Novem- 
ber and  December.  It  was  found  that  the  fly  never  attacked  these 
crops,  and  of  late  years  there  has  been  but  little  complaint  of  this 
once  dreaded  insect. 

12.  The  Fly  Weevil,  Butalis  Cerealella. 

The  name  weevil  is  given  to  six  different  kinds  of  insects  in  this 
country  ;  two  of  which  are  flies,  two  moths,  and  two  beetles.  One 
of  these,  the  fly  weevil,  called  also  Angoumois,  grain  moth,  is  a  great 
pest  to  granaries  in  the  Southern  States.  It  is  a  small  moth  of  a  pale 
cinnamon-brown  color,  with  narrow  fringed  hind  wings  of  a  leaden 
color,  with  two  tapering  feelers  turned  over  its  head.  It  lays  sixty 
or  ninety  eggs  in  clusters  of  twenty  or  more  on  a  single  grain.  These 
eggs  hatch  out  a  diminutive  worm  not  thicker  than  a  hair,  each  of 
which  selects  a  grain  of  wheat  to  itself,  and  burrows  in  the  softest 
part,  eating  out  all  the  substance,  leaving  nothing  but  a  shell 
behind.  (Harris's  Insects,  p.  500.) 

The  ravages  of  this  fly  weevil  have  been  effectually  checked  by 
kiln  drying  the  wheat.  It  is  stated  that  twelve  hours  of  heat  equal 
to  167°  t.  has  effectually  killed  every  vestige  of  the  insect  in  a 
badly  infested  grain.  Many  farmers  in  the  South  have  adopted  the 
plan  of  wheat  houses  with  movable  roofs,  with  good  effect.  A  few 
days  hot  sun,  and  keeping  the  wheat  well  stirred,  will  kill  out  this 
moth.  Some  also  adopted  the  plan  of  keeping  their  wheat  in  very 
cool,  dry  apartments,  which  seems  to  prevent  the  hatching  of  the 
eggs.  This  is  particularly  true,  when  kept  in  small  bulk  as  in  sacks 
where  a  heating  process  cannot  take  place. 


392 


APPENDIX 


13.  The  Black  Weevil,  Calandra  Oryzm, 

This  is  tlie  rice  weevil  of  the  Southern  States,  but  it  is  we]l  known 
a.mong  wheat  raisers  as  a  very  destructive  insect  in  their  granaries. 
It  is  a  slender  black  beetle,  very  similar  according  to  Harris,  to  the 
wheat  weevil  of  Europe  (Calandra  granaria),  only  this  is  of  a  pitchy 
red  color. 

The  black  weevil  bores  a  hole  in  a  grain  of  rice  or  wheat,  in 
which  it  deposits  a  single  egg,  and  thus  continues  from  grain  to 
grain  until  all  her  eggs  are  laid.  She  then  dies,  leaving  the  grain 
however  well  stocked  for  a  future  harvest  of  weevil  grubs. 

After  the  eggs  hatch,  the  grub  lives  securely  and  unseen  in  the 
centre  of  the  grain,  feeding  upon  it,  and  thus  deteriorating  both  the 
quantity  and  quality  of  the  rice  or  wheat  as  the  case  maybe.  When 
fully  grown  it  escapes  at  one  end,  leaving  a  little  hole,  which  it 
artfully  closes  with  particles  of  flour. 

This  generally  occurs  during  the  winter  when  they  are  changed 
into  the  pupa  state.  In  the  following  spring  they  are  transformed 
into  beetles  and  come  out  of  the  grains,  when  by  winnowing  and 
sifting  they  may  be  separated  from  the  grain  and  destroyed. 

This  weevtl  also  depredates  upon  Indian  corn,  but  is  perhaps 
more  destructive  to  rice  than  either  wheat  or  corn. 


IV. 

THE  OAT. 

AVENA  SATIVA. 

1.  Climatic  and  Botanical  Relations 

The  oat  now  so  extensively  cultivated  in  this  country  was  brought 
from  the  Old  World.  There  are  several  varieties  cultivated,  as  the 
black  oat  (Avena  nigra),  skinless  oat  (Avena  nuda),  horse  mane  oat 
(Avena  secunda),  bearded  oat  (Avena  strigora),  etc. 

The  common  cultivated  oat  contains  two  or  three  seeds  in  one 
inflorescence.  It  has  a  loose  panicle  of  large  drooping  spikelets,  the 
florets  investing  the  grain,  one  flower  with  a  large  twisted  awn  on 
the  back,  the  other  awnless.  (Gray.) 


APPENDIX. 


393 


The  oat  is  a  native  of  cold  climates.  It  flourishes,  however,  in 
temperate  latitudes  ;  but  degenerates  as  you  approach  the  equator. 
It  has  been  cultivated  in  Bengal  as  low  as  the  twentv-fifth  degree 
latitude.  It  is  cultivated  successfully  in  the  United  States  from 
Maine  to  Florida. 

2.  Its  Uses  and  Habitudes. 

Oatmeal  is  the  principal  bread  food  of  the  working  classes  in  the 
northern  part  of  Great  Britian.  It  is  quite  nutritive,  the  Scotch  oat 
having,  according  to  analysis,  743  parts  in  1000  of  soluble  nutritive 
matter.  Next  to  maize  it  is  the  great  stock  food  of  the  Southern 
and  Western  States,  but  it  is  rarely  used  in  this  country  as  food  for 
man  except  as  a  porridge  in  the  northern  cities. 

The  oat  is  a  coarse  feeder,  and  is  not  very  dainty  in  its  selection 
of  soil  in  which  to  grow.  Unlike  wheat,  it  grows  on  stubble  land 
without  being  reploughed,  and  will  even  produce  three  very  good 
crops  in  succession  from  its  own  seeding  on  good  laud.  This  is 
termed  volunteer  oats.  On  this  account  it  is  well  adapted  to  the 
scarce  labor  and  loose  methods  of  Southern  farming. 

It  is  a  thirsty  plant,  however,  and  luxuriates  in  low  lands  -where 
its  roots  can  get  a  good  supply  of  w^ater  from  the  soil.  Fall  oats 
always  succeed  well  when  a  stand  is  obtained,  because  of  the  season- 
able winter  rains.  Spring  oats  frequently  fail  in  the  South,  on 
account  of  dry  weather,  hence  no  farmer  should  rely  on  this  crop 
exclusively.  The  most  successful  plan  is  to  have  tw^o  or  three 
sowings  from  October  to  January. 

3.  The  Oat  as  an  Exhauster  of  the  Soil. 

A  general  opinion  prevails  among  farmers,  that  the  oat  is  very 
exhausting  to  land ;  so  much  so,  that  some  are  prejudiced  against 
it  as  a  leading  crop.  Many  of  these  traditional  notions  are  well 
founded,  although  resulting  from  empiricism  rather  than  science, 
and  should  be  carefully  investigated. 

In  comparing  the  analysis  of  the  oat  with  the  other  cereals,  there 
is  no  remarkable  difference  between  them  only  in  reference  to  silica. 
In  fact,  the  more  important  constituents,  as  phosphoric  acid  and 
potash,  existing  more  sparingly  in  it,  than  in  w^ieat  or  Indian 
corn. 

In  100  parts  of  the  oat  grain,  there  is  3.07  of  ash.  Of  this, 46.4 
is  silica.    Of  the  straw,  there  is  5.12  per  cent,  of  ash  ;  48.7  of  w^iich 

17* 


39i 


APPENDIX. 


is  silica.  This  would  carry  off  from  an  acre,  in  a  crop  of  15  bushels, 
6.83  pounds  of  soluble  silica  in  the  grain,  and  16.20  pounds  in  the 
straw,  equal  to  23  pounds.  A  crop  of  ten  bushels  of  wheat  would 
carry  off  only  about  15  pounds,  and  all  the  other  cereals  less  than 
this.  As  the  stalk  of  Indian  corn  is  left  on  the  field,  the  amount 
carried  off  by  the  grain  would  be  a  very  small  fraction. 

While  silica  is  not  deemed  an  important  constituent  of  fertilizers, 
because  of  its  abundance  in  all  soils,  yet,  when  exhausted  in  such 
quantities  as  by  the  oat  crop,  taken  in  connection  with  the  general 
impression  of  practical  farmers  that  it  is  an  exhausting  crop,  it  be- 
comes a  matter  worthy  of  investigation.  For  while  it  is  true  that 
silica  abounds  in  all  soils,  it  is  not  true  that  soluble  silica  does. 

But  while  the  oat  crop,  on  account  of  the  soluble  silica  it  carries 
off  from  a  soil,  might  be  detrimental  for  a  succession  of  cereal  crops, 
it  would  not  in  a  rotation  with  cotton,  peas,  or  turnips,  as  neither  of 
these  demands  silica  as  a  prime  ingredient.  We  have  long  been  con- 
vinced that  oats  and  cotton  form  the  best  rotation  for  the  Southern 
States,  and  this  investigation  confirms  us  in  the  opinion. 

4.  Diseases  of  the  Oat. 

The  oat  is  a  hardy  plant,  and  not  subject  to  many  diseases.  It 
however,  is  sometimes  injured  by  the  black  blast,  a  parasite  which 
destroys  the  entire  head.  Also  a  similar  rust  to  that  which  attacks 
wheat.  Both  of  these  diseases  are,  we  doubt  not,  aggravated  by 
imperfect  seed ;  for  no  crop  seems  to  suffer  more  from  this  cause 
than  the  oat  crop.  If  more  pains  were  taken  in  the  selection  of 
vigorous,  healthy  seed,  by  similar  plans  recommended  in  reference 
to  wheat,  we  would  hear  but  little  of  rust  and  blast  in  the  oat  crop. 
Good  seed,  good  cultivation,  and  good  fertilizers  will  go  far  toward 
relieving  any  of  our  crops  from  the  diseases  which  commonly  infest 
them. 


APPENDIX. 


395 


V. 

THE  GEASSES. 

BoTANiCALLY  Speaking,  tlie  grasses  belong  to  the  order  Gramineae, 
but  in  agriculture,  the  term  embraces  plants  of  other  orders.  In 
fact,  all  the  herbage  of  the  field  upon  which  cattle  feed,  either  as 
pasturage  or  forage,  is  embraced  under  this  general  term.  We  shall 
only  treat  of  such  as  are  of  great  interest  to  the  agriculturist. 

There  are  said  to  be  130  distinct  native  species  and  varieties  of 
grasses  in  Great  Britain  ;  and  probably  more  than  double  that  many 
in  the  United  States.    Botanists  have  described  over  300  varieties. 

As  to  the  nutrient  qualities  of  the  grasses,  Mr.  G.  Sinclair  says, 
that  grasses  with  culms,  having  swollen  joints,  thick  and  succulent 
leaves,  and  flowers  with  downy  husks,  contain  more  sugar  and 
mucilage  than  others ;  while  those  having  culms  with  numerous 
joints,  smooth  and  succulent  leaves,  flowers  in  a  close  panicle,  and 
large  blunt  florets,  contain  more  gluten  and  mucilage. 

1.  Bed  Clover,  Trifolium  Pratense. 

This,  the  most  valuable  of  what  are  termed  grasses  in  agriculture, 
belongs  to  the  Leguminosae.  It  is  useful  in  American  husbandry,  not 
only  as  a  pasturage  and  forage  crop,  but  as  an  improver  of  the  soil. 

Its  climatic  preferences  restrict  it  to  the  Northern  and  Middle 
States,  and  the  mountainous  districts  of  the  Southern  States.  The 
plain  country  of  the  Cotton  States  seems  to  be  too  dry  and  hot  for  it, 
although  even  here  it  succeeds  very  well  on  low,  rich,  moist  lands. 
But  it  cannot  be  relied  upon  as  a  field  crop  in  the  South. 

The  red  clover  ameliorates  the  soil  in  several  ways.  It  has  a  tap 
root  which  penetrates  deeper  than  most  plants,  and  thus  brings  up 
nutriment  to  the  stems  and  leaves,  without  exhausting  so  much  the 
the  surface  soil.  Even  after  the  hay  is  cut  and  removed,  the  roots 
which  remain,  not  only  loosen  the  soil  by  their  ramifications,  but 
add  much  to  its  nutriment,  especially  in  the  important  element  of 
nitrogen. 

The  proximate  analysis  of  red  clover  is  given  in  this  work,  under 
the  article  of  Indian  corn,  showing  that  as  a  cattle  food  it  is  equal 


396 


APPENDIX. 


to  any  of  the  forage  plants ;  and  as  a  milk  and  blood  producing 
article,  excels  all  others  except  lucerne  (itself  a  species  of  clover), 
and  the  Hungarian  millet. 

2.  Timothy  or  Cafs-tail  Grass,  Phleum  Pratense. 

This  is  one  of  the  most  valuable  grasses  known  to  American 
farmers.  It  is  perennial,  and  a  native  of  Great  Britain.  It  was 
named  in  honor  of  Timothy  Hanson,  Esq.,  who  first  introduced  the 
seeds  into  Maryland.  It  is  called  herd's  grass  in  New  England,  a 
name  given  to  the  Agrotis  vulgaris,  or  red  top,  in  the  Middle  and 
Southern  States. 

Its  analysis  (the  cured  hay),  shows  7.01  per  cent,  of  mineral  mat- 
ter, of  which  there  is  35.6  of  silica,  28.8  of  potash,  and  10.8  of  phos- 
phoric acid  ;  being  the  three  principal  constituents  of  the  ash.  The 
proximate  analysis  has  of  albuminoids  9.7,  carbo-hydrates  48.8,  and 
fat,  3.0. 

It  flourishes  in  the  Northern  and  Middle  States,  but  will  not 
produce  well  in  the  Cotton  States. 

3.  Lucern,  Medicago  Satlva. 

This  a  perennial  plant,  and  one  of  the  best,  if  not  the  very  best, 
for  the  Southern  States.  It  may  be  used  green,  or  as  dry  forage. 
Sowed  on  good  land,  two  and  a-lialf  feet  apart,  it,  will  make  several 
tons  of  the  most  nutritious  hay  jDor  acre.  One  seeding,  properly 
cared  for,  will  last  ten  or  fifteen  years.  It  should  never  be  depas- 
tured, however,  as  the  destruction  of  the  crown  of  the  plants,  by 
grazing  and  tramping  of  the  cattle,  causes  the  plants  to  die. 

Lucern  is  green  every  month  in  the  year,  except  the  three 
winter  months.  It  begins  to  put  forth  its  leaves  late  in  February, 
and  is  ready  to  cut  several  weeks  before  the  red  clover.  Three  or 
four  cuttings  may  be  made  in  a  year,  on  rich  land,  either  for  soiling 
or  forage. 

It  is  the  most  nutritious  of  all  the  grasses,  the  hay  of  the  young 
plants  having  19.7  per  cent,  of  albuminoids,  carbo-hydrates  32.9, 
and  fat,  3.3.  The  per  cent,  of  ash,  amounts  to  7.14,  of  which  there 
is  25.3  of  potash,  and  48.0  lime. 

4.  Crab  Grass,  Digitaria  Sanguinalis. 

This  is  a  well-known  annual  of  the  Southern  States,  which 
comes  up  freely  on  the  cotton  beds,  and  is  a  great  pest  to  the 


APPENDIX. 


397 


farmer.  It  is,  however,  a  good  grass  for  hay,  being  very  nutritious, 
admitting  of  several  cuttings  on  good  lands,  of  a  seasonable  year. 

There  is  no  need  of  ever  sowing  the  seed,  as  there  always  seems 
to  be  enough  on  ploughed  land,  to  produce  a  good  crop  of  hay.  If  a 
farmer  designates  a  portion  of  land  for  hay,  he  has  Only  to  give  it  a 
thorough  ploughing  and  manuring,  if  poor ;  and  should  a  crop  of 
weeds  come  up,  give  it  the  second  or  even  a  third  ploughing  ;  there 
will  then  in  most  cases  be  a  plenty  of  seed  for  a  good  crop  of  hay. 
Of  wet  summers,  a  good  crop  may  be  thus  secured  after  small  grain. 

A  principal  reason  why  crab-grass  hay  is  not  valued  highly  at  the 
South,  is  because  it  is  generally  gathered  and  sold  by  negroes  as  their 
own  crop ;  and  it  is  frequently  over-ripe,  and  not  properly  cured, 
the  dew  being  allowed  to  fall  upon  it.  If  cut  in  the  blossom,  and 
put  up  in  cocks  at  night,  so  as  to  prevent  the  damage  by  dew,  and 
then  spread  out  for  another  day's  sun,  and  housed  or  stacked  that 
evening,  it  makes  as  sweet  and  nutritious  hay  as  any  of  the  northern 
grasses. 

5.  Blue  Grass,  Poa  Pratensis. 

This,  the  far-famed  Kentucky  blue  grass,  is  perhaps  the  most 
valuable  grass  in  America.  It  delights  in  calcareous  soils,  and  grows 
spontaneously  in  the  rice  limestone  lands  of  the  West.  It  grows  very 
well  in  woodlands,  but  luxuriates  in  fields  on  which  the  sun  exerts 
full  power.  Horses  and  cattle  become  fatter  on  this  grass  without 
grain  than  any  other  pasturage  grass. 

The  blue  grass,  sown  on  a  soil  adapted  to  it,  will  soon  expel 
every  other  species  of  grass.  It  should  be  sown  in  September  or 
October,  but  will  do  very  well  sown  in  the  spring,  if  the  season  is 
favorable.  That  grown  in  open  land  is  much  more  abundant  and 
nutritious  than  that  on  woodland,  and  will  keep  a  larger  amount  of 
stock  on  the  same  area  of  land. 

6.  Bermuda  Grass,  Digitaria  Dactylon. 

This  valuable  grass  was  introduced  into  Georgia,  from  the  island 
of  Bermuda,  in  the  early  part  of  the  present  century,  by  Hon.  Thomas 
Butlar  King,  or  Mr.  Couper.  It  is  familiarly  known  throughout  the 
south  as  wire-grass.  The  generic  name  Digitaria  dactylon  is  by 
Elliot. 

The  Bermuda  grass,  according  to  Mr.  Spalding,  is  identical  with 
douh  grass  of  India  (Cynodon  dactylon) ;  but  there  seems  to  be  some 


398 


APPENDIX. 


difference,  as  the  fact  tliat  the  Bermuda  has  no  seed,  while  the  doub 
grass  has.  They  no  doubt  belong  to  the  same  species,  as  does  an- 
other variety  of  creeping  wire-grass  at  the  South,  which  can  not  be 
distinguished  from  it  without  close  inspection. 

It  has  no  seed,  and  is  propagated  entirely  by  layers,  each  joint 
answering  for  one  and  taking  root  readily.  It  is  in  fact  so  tenacious 
of  life  and  so  difficult  of  extirpation,  that  it  is  deemed  a  great  pest 
by  most  planters.  Indeed  it  would  be  the  extremest  folly  for  any 
farmer  to  plant  it  indiscriminately  in  his  fields.  Many  of  the  best 
bottom  lands  in  some  sections  of  Georgia  are  so  usurped  by  it  as  to 
be  entirely  useless  for  cultivation. 

It  will  not  grow  on  sandy  land,  but  demands  a  stiff  tenacious 
clay  for  its  propagation.  Hence  it  luxuriates  on  the  red  clay  hills 
of  the  South,  and  if  properly  attended  to,  would  soon  intercept  the 
washes,  and  restore  these  worn  out  gullied  slopes  into  fine  pastur- 
age lands. 

From  a  recent  analysis  of  Dr.  Ravanel,  it  has  14  per  cent,  of  albu- 
minoids, which  places  it  in  the  first  rank  of  pasturage  grasses.  On 
rich  lands  it  makes  a  luxuriant  crop  of  hay,  of  the  most  nutritive 
character.  On  common  uplands,  however,  it  rarely  grows  tall  enough 
for  the  sickle. 

Cows,  sheep,  and  all  kinds  of  stock,  will  leave  all  other  herbage 
for  it,  and  it  is  prospectively  the  grass  of  the  South.  If  a  planter 
should  devote  his  hills  to  this  grass,  and  his  level  lands  to  corn  and 
cotton,  adopting  a  mixed  husbandry,  the  country  would  not  only  be 
enriched  but  beautified.  For  on  the  hills,  where  the  soil  is  not  very 
rich,  he  could  every  few  years  have  a  rotation  in  corn,  cotton,  or 
oats,  which  would  well  repay  him,  not  only  for  the  crop  produced, 
but  the  subsequent  value  of  the  pastarage. 

It  is  beyond  all  question  the  grass  to  renovate  the  worn-out  hilly 
lands  of  the  Cotton  States.  The  roots  penetrate  a  considerable  depth, 
and  produce  a  large  amount  of  organic  matter  which  opens  and  en- 
riches the  soil.  Wherever  Bermuda  grass  fields  have  been  culti- 
vated, the  grass  being  properly  subjected,  the  product  has  been  re- 
markable, owing  no  doubt  mainly  to  the  increase  of  nitrogen. 

After  pasturing  for  several  years,  a  farmer  can  prepare  a  grass 
sward  for  a  cultivated  crop  as  follows :  Run  a  coulter  plough 
through  it,  and  cross  plough  it  so  as  to  admit  a  turning  shovel. 
The  roots  turned  up  to  the  frost  will  soon  be  killed,  and  several 
plougliings  of  this  character  during  the  winter,  will  prepare  the 


APPENDIX. 


399 


land  for  cultivation  in  peas  or  corn.  A  good  crop  of  oats  might  be 
produced  the  next  winter,  and  the  grass  left  for  pasturage  again. 

While  the  Bermuda  is  not  a  winter  grass,  yet  in  the  mild  winters 
of  the  South,  it  affords  a  luxuriant  pasturage,  properly  managed. 
The  field  or  lot  intended  for  winter  use,  should  not  be  touched  dur- 
ing the  year,  until  the  frost  comes,  and  kills  the  tops.  Then  the 
cattle  might  browse  upon  it,  and  lastly  the  sheep,  who,  with  their 
narrow  mouths,  would  eat  the  green  stems  into  the  very  ground, 
which  had  been  protected  by  the  thick  coating  of  grass.  In  this 
way,  the  Bermuda  might  be  made  subservient  as  a  pasture  for  ten 
months  of  the  year. 

The  only  effectual  mode  of  extirpation  is  repeated  ploughings 
and  rakings,  and  even,  then  unless  carefully  watched  in  after  culti- 
vation, a  field  will  soon  be  re-set  with  it.  The  only  plant  that  has 
effectually  mastered  it,  so  far  as  our  observation  goes,  is  the  Japan 
clover  (Lespedeza  striata),  which  has  spread  over  the  Southern  States 
during  the  last  ten  or  twelve  years,  supposed  to  have  been  introduced 
in  a  vessel  from  Japan,  as  it  was  first  discovered  on  the  commons  of 
Charleston.  Many  Bermuda  grass  fields  have  been  superseded  by 
this  new  species  of  clover. 


VI. 

THE   TOBACCO  PLANT. 

NICOTIANA  TABACUM. 

This  narcotic,  now  so  extensively  used,  is  a  native  of  North 
America.  John  Nicot,  who  was  ambassador  of  the  King  of  France 
to  Portugal,  procured  some  seeds  from  a  Dutchman,  who  brought 
them  from  Florida.  Nicot  presented  the  first  plant  to  Catherine  de 
Medicis ;  and  botanists  honored  him  with  the  generic  name.  The 
common  name  was  derived  from  the  Island  of  Tobago,  West 
Indies,  whence  it  was  originally  brought.  It  was  known  in  Europe, 
according  to  Linnseus,  as  early  as  1560. 

Tobacco  is  a  powerful  narcotic,  and  a  soothing  stimulant  to  the 
nervous  system.  It  has  on  this  account  become  an  extensive  article 
of  commerce,  and  an  important  item  of  agricultural  production  in 
this  country. 


400 


APPENDIX. 


Tobacco  is  an  annual  plant,  and  may  be  brought  to  maturity  in 
any  clime  ;  even  in  Russia  and  Sweden  ;  but  it  does  not  obtain 
sufficient  size  for  successful  culture,  nor  is  the  flavor  as  good  as 
when  grown  in  a  more  genial  clime. 

In  this  country  it  is  cultivated  successfully  in  the  Connecticut 
valley ;  but  the  principal  tobacco  States,  are  Virginia,  North  Caro- 
lina, Kentucky,  and  Missouri.  Not  only  is  the  soil  well  adapted, 
but  the  inhabitants,  from  long  use,  are  better  versed  in  its  culture 
and  preparation  for  market. 

For  the  proper  culture  of  tobacco  plants,  beds  are  always  neces- 
sary. New  ground,  which  has  never  been  exhausted  by  cropping, 
is  the  best.  After  removing  all  the  grubs,  brush  heaps  are  piled 
upon  it  during  the  winter,  and  burned  off  in  the  early  spring.  This 
furnishes  a  good  supply  of  potash,  so  much  needed  by  the  tobacco 
plant.  The  young  plants,  after  taking  good  root,  are  transplanted 
to  the  fields  after  a  rain,  in  hills  three  to  four  feet  apart  each  way. 
The  land,  if  not  rich,  should  be  well  fertilized,  and  cultivated  with 
the  plough  and  hoe,  very  much  like  corn  or  cotton. 

The  analysis  of  the  tobacco  plant  is  remarkable  for  the  amount  of 
ash  or  mineral  matter  indicated  by  it.  The  average  of  seven  anal- 
yses shows  24.08  per  cent,  of  ash,  of  which  in  100  pounds  there 


would  be 

Potash  27.4 

Soda  3.7 

Magnesia  10.5 

Lime  37.0 

Phosphoric  acid  3.6 

Sulphuric  acid  3.9 

Silica    9.6 

Chlorine  4.5 


From  this  it  would  seem  that  potash  and  lime  are  rapidly  ex- 
hausted from  soils  by  the  tobacco  crop  ;  and  it  has  been  found  that 
fertilizers  containing  them,  are  very  important  to  be  applied  to  the 
old  tobacco  lands  of  Virginia  and  Maryland. 


APPENDIX. 


401 


VII. 

THE  CEYPTOGAMS. 

This  series  embraces  quite  a  number  of  fungi,  and  microscopic 
plants  of  considerable  interest  in  agriculture.  We  will  speak  of 
them  as  tliey  come  up  incidentally,  in  their  relations  to  other  plants 
or  their  products,  as  some  of  them  are  very  active  as  parasites  and 
ferments. 

Several  of  them  have  been  used  as  food  for  man,  and  on  that  ac- 
count demand  a  brief  description  here.  The  common  mushroom 
(Agaricus  campestris),  the  truffle  (Tuber  cibarium),  and  morel 
(Morchella  esculenta),  are  considered  delicacies  with  many  people. 
Thirty-three  different  fungi  are  eaten  by  the  Russians.  Some  of 
this  class,  however,  are  very  poisonous,  and  it  is  important  to  know 
how  to  distinguish  them.  Dr.  Christison  says,  those  which  have  a 
warty  cap,  with  fragments  adhering  to  their  upper  surface,  are  gen- 
erally  poisonous.  Those  which  are  heavy  as  to  weight,  and  have  an 
unpleasant  odor,  and  emerge  from  a  vulva  or  bag,  are  also  hurtful. 
Those  also  should  be  avoided  which  are  moist  on  the  surface,  and 
grow  in  woods  and  shady  places ;  as  well  as  those  which  grow  in 
tufts  or  clusters  from  stumps  and  trunks  of  trees.  A  pungent  odor 
and  styptic  taste  he  regards  as  sure  tests  for  poisonous  mushrooms  ; 
and  those  which  become  blue  as  soon  as  cut,  are  invariably  poison- 
ous. Also,  those  which  have  a  rose-red  color,  a  corky  texture,  and 
a  membranous  collar  around  the  stem.  The  easiest  mode,  how- 
ever, of  testing  the  quality  of  fungi,  is  to  introduce  a  silver  spoon 
or  coin  into  the  vessel  in  which  they  are  boiling;  if  the  silver 
assumes  a  bluish  black,  it  is  evidence  of  the  presence  of  poisonous 
I  fungi. 

An  edible  fungus  (Scleroticum  cocos,)  called  tuckahoe  or  "  Indian 
bread  "  by  the  early  settlers,  is  found  in  the  South.  It  grows  under- 
ground, and  was  formerly  often  ploughed  up  by  the  negroes,  and 
^  used  by  them  also,  in  some  instances,  as  well  as  by  the  aborigines, 
as  bread.  The  following  analysis  of  a  specimen  from  Virginia,  by 
Dr.  Torrey,  shows  it  to  be  rather  deficient  in  nutritive  qualities.  It 


402 


APPENDIX. 


had  glucose,  0.93 ;  gum  (Arabin),  and  pectin  2.60 ;  and  pectose,  17.84 ; 
the  remainder  was  cellulose,  insoluble  nitrogenous  matter,  water, 
and  ash. 

vm. 

WATER  CULTURE. 

In  order  to  ascertain  exactly  "  the  role  which  the  mineral  ingre- 
dients of  plant  food  play  in  the  vital  processes  of  cultivated  plants," 
the  expedient  of  water  culture  has  been  adopted  in  the  experimental 
stations  of  Germany,  under  the  direction  of  Dr.  Nobbe.  It  was  be- 
lieved that  not  all  of  the  mineral  elements  found  in  plants,  were 
essential  to  their  growth  and  full  development,  and  to  ascertain 
which  were  the  accidental  or  superfluous,  if  any,  these  investigations 
were  made.  No  soil  could  be  /ound,  or  made  so  free  from  these  in- 
gredients, as  to  make  a  safe  and  satisfactory  solution  of  the  question 
It  was  found  that  after  seeds  have  germinated  in  moist  sand  or  cot- 
ton, and  then  suspended  with  their  roots  in  water,  they  would  thrive 
if  the  necessary  food  was  held  in  solution  by  the  water.  Thus, 
by  adding  all  the  essential  elements  but  one  (potash  or  soda  for 
instance),  it  could  be  ascertained  which  of  these  were  most  essential 
to  plant  life. 

German  chemists,  as  Knop,  Sachs,  Nobbe,  Siegart,  Wolfi,  and 
Kuehn,  have  carried  water  culture  to  very  successful  results  for  the 
last  few  years,  and  determined  some  very  interesting  facts.  Plants 
have  been  raised  in  this  way  as  large,  healthy,  and  well-grown,  as 
in  the  soil.  Nobbe  obtained  a  Japanese  buckwheat  plant,  nine  feet 
high,  weighing,  air-dry,  4,786  times  more  than  the  seed,  and  bearing 
796  ripe,  and  108  imperfect  seeds.  And  Knop  has  a  young  oak, 
which  has  thus  far  grown  normally,  with  its  roots  only  in  aqueous 
solution. 

While  this  species  of  culture  is  outside  of  all  of  our  precon- 
ceived notions  of  agriculture,  as  an  art  or  a  science,  we  may  hope 
for  one  practical  result  from  it,  which  if  accomplished,  will  be  bene- 
ficial, viz.,  the  exact  formula  for  the  proper  support  and  nourish- 
ment of  each  plant.  Thus,  if  it  be  established  that  soda  is  not 
essential  to  the  production  of  buckwheat  (as  these  experiments 


APPENDIX. 


403 


teach),  it  may  always  be  left  out  in  a  fertilizer  for  buck wli eat,  and 
60  on  through  the  whole  list  of  plants.  Much  can  also  be  ascertained 
as  to  the  relative  amount  of  the  elements  needed  for  each  plant. 

Thus  far,  some  very  strange  results  have  been  reached  ;  as  for 
instance,  that  silica  which  enters  so  largely  into  the  composition  of 
the  cereals,  especially,  seems  not  to  be  an  essential  ingredient  in 
the  most  commonly  cultivated  plants.  That  chlorine  is  needful  to 
some,  as  buckwheat  and  vetches ;  while  soda,  if  essential  at  all,  is 
so  in  the  most  minute  quantities.  That  in  addition  to  the  four 
organic  elements,  potash,  lime,  magnesia,  iron,  phosphoric  and  sul- 
phuric acids,  are  the  only  ingredients  absolutely  essential  for  the 
life  and  normal  growth  of  agricultural  plants. 

This  upsets  all  of  our  preconceived  notions  of  the  chemistry  of 
plants  ;  as  it  has  always  been  supposed  that  silica  and  soda,  which 
enter  so  largely  into  most  agricultural  plants,  were  among  the  most 
essential  and  important ;  while  iron,  which  has  been  found  only  in 
minute  quantities,  was  deemed  altogether  accidental.  Xow,  the 
observations  made  by  Gris,  in  1843,  have  since  been  substantiated 
by  numerous  experimenters,  that  iron  is  important  in  the  proper 
development  of  chlorophyl  in  the  leaves  of  plants.  2s  obbe  has  also 
shown  that  chlorine,  existing  as  it  does  so  minutely  in  most  plants, 
is  necessary  to  the  normal  formation  of  the  seeds  of  buckwheat; 
that  w^ithout  it,  the  transfer  of  starch  from  the  leaves  when  it  is 
elaborated  to  the  flower  and  the  fruit  is  prevented ;  and  the  leaves 
and  st-em  become  diseased.  These  results  have  been  corroborated 
by  experiments  of  Beyer. 

From  a  series  of  experiments  with  maize,  buckwheat,  cress,  oak, 
and  horse-chestnut,  in  solutions  free  from  chlorine,  Knop  concluded 
that  this  element  was  not  essential  to  the  perfection  of  these  plants. 

With  a  view  to  ascertain  the  function  of  potash  in  vegetable  life, 
two  series  of  experiments  were  entered  into,  under  the  direction  of 
Nobbe,  one  with  buckwheat,  and  the  other  with  rye.  In  the  normal 
solutions,  the  plants  grew  several  feet  in  height,  and  seemed  to  be 
perfect  in  development.  Without  potash  they  were  only  a  few 
inches  in  height ;  and  micro-chemical  investigations  showed  no 
starch  in  the  leaves,  which  obviously  caused  their  stunted  growth. 
The  inference  is  that  without  the  cooperation  of  potash  in  the 
chlorophyl  grains,  no  starch  is  formed. 

Of  the  different  salts  of  potash,  the  chloride  was  the  most 
eflacient  form  for  the  buckwheat  plant.    The  nitrate  stood  next. 


404 


APPENDIX. 


Tlie  sulphate  and  phospliate  seemed  to  produce  a  disease,  wliich 
was  due  to  tlie  fact  that  the  starch  formed  in  the  chlorophyl  grains, 
accumulates  passively  in  the  leaves,  instead  of  being  taken  up  to  be 
utilized  in  the  development  of  the  plant.  It  was  also  concluded 
that  potassium  could  not  be  replaced  physiologically,  by  sodium  or 
lithium.  While  the  sodium  was  deemed  harmless,  it  was  useless ; 
the  lithium,  however,  had  a  positively  injurious  effect  on  the  plant 
tissues. 

Experiments  on  summer  rye  produced  similar  results. 

The  potassium  seems  to  be  essential  for  the  building  up  of 
starch,  in  the  chlorophyl  grains.  The  experiments  at  least  proved 
this  to  be  one  of  the  offices  of  potash. 

While  these  experiments  are  very  interesting,  and  may  serve  to 
teach  us  several  important  truths,  it  should  be  remembered  that 
they  are  not  of  universal  application.  Other  plants  may  fail  to 
appropriate  nutrition  without  the  natural  medium  of  the  soil,  and 
may  show  a  very  different  behavior  as  to  elements  rejected  by  these. 

Experiments  made  the  present  year  (1874),  at  the  experimental 
station,  at  Athens,  Georgia,  show  very  conclusively  that  so  far  as 
the  cotton  plant  is  concerned,  soda  is  about  as  important  as  potash. 

We  took  river  sand  from  shoaly  water,  out  of  which  all  the  sol- 
uble matters  had  been  com]3letely  washed,  and  put  in  flower-pots. 
In  one  which  had  all  the  plant  constituents  except  soda ;  the  plant 
was  very  sickly  and  diminutive,  showing  no  disposition  to  produce 
fruit  by  the  formation  of  a  flower-bud.  That  without  potash  had 
hardly  so  healthy  a  foliage,  but  produced  a  very  minute  fruit-germ. 
The  one  minus  the  phosphoric  acid,  developed  a  pigmy  stalk,  with 
two  small  leaves  ;  and  when  the  phosphoric  acid  existing  in  the 
pabulum  of  the  seed  was  exhausted,  it  then  ceased  to  grow  altogether. 

One  fact  in  reference  to  the  nitrates,  as  contrasted  with  albumi- 
noids as  fertilizers,  is  worthy  of  note.  Our  results  corresponded 
with  experiments  in  Germany  and  France,  as  to  the  superior  effect 
of  the  nitrates  in  flower-pots  and  sand.  In  the  one  containing 
nitrate  of  soda,  the  cotton  plant  grew  more  rapidly  than  in  those 
containing  ammonia  and  animal  matter  representing  organic  nitro- 
gen. The  latter  was  considerably  behind  the  others  at  first,  but 
gradually  gained  upon  them,  and  came  out  nearly  equal. 

In  the  open  field  just  the  reverse  was  true.  Two  rows  of  cotton, 
each  35  yards  long,  were  fertilized  with  different  nitrogenous  ma- 
nures, each  of  them  combined  with  27  ounces  of  superphosphate. 


APPENDIX. 


405 


and  containing  severally  as  follows  :  Guanape  203^  ounces,  equal  to 
about  two  ounces  of  nitrogen  as  ammonia  :  Nitrate  of  soda,  13^^ 
ounces,  equal  to  7  ounces  nitrogen  :  Sulphate  of  ammonia,  IB}^ 
ounces,  equal  to  3  ounces  of  nitrogen  :  Cotton-seed  cake,  54  ounces, 
equal  to  33^  ounces  nitrogen  :  dried  blood,  27  ounces,  equal  to  four 
and  a  half  ounces  of  nitrogen  ;  and  animal  matter,  27  ounces,  equal 
to  3  ounces  of  nitrogen. 

The  following  is  the  result  from  the  two  first  pickings  of  cotton  : 


Guanape  135  ozs.  Seed  cotton 

Nitrate  of  soda  54  "  " 

Sulphate  of  ammonia  114  " 

Cotton- seed  cake  141   "  " 

Dried  blood  150  " 

Animal  matter,  (dried  flesh) . . .  136  "  " 


It  will  thus  be  perceived,  that  nitrogen  in  the  form  of  a  nitrate, 
and  at  about  an  equal  cost,  is  far  behind  ammonia  and  organic  ni- 
trogen, as  albuminoids  in  the  substances  used. 

This  shows  conclusively  that  experiments  of  an  abnormal  cha- 
racter, as  water  culture,  and  in  flower-pots  of  sand,  cannot  be  relied 
upon  in  the  elucidation  of  agricultural  science.  In  order  for  this, 
the  open  field  with  a  natural  soil,  and  usual  cultivation ;  the  sun- 
shine, winds,  and  rains ;  day  and  night ;  the  processes  of  decay  in 
the  soil,  and  evaporation  from  it ;  of  nitrification,  absorption,  and 
elimination  ;  the  action  of  clay  and  sand  ;  of  humus,  and  all  the 
soluble  salts  in  the  soil,  with  their  play  of  chemical  afiinities;  the 
sinking  of  hydrostatic,  and  the  rising  of  capillary  waters,  all  these, 
and  others  that  might  be  mentioned,  which  are  entirely  or  partially 
excluded  from  abnormal  processes,  are  essential  in  order  to  de- 
termine the  value  of  plant  constituents,  or  the  laws  which  govern 
vegetable  life,  growth,  and  nutrition. 


406 


APPENDIX. 


IX. 

TABLES  OF  AGEICULTUEAL  PEODUCTS. 

Table  I. 

Composition  of  Agricultural  Plants  and  Products,  air-dry,  taken 
from  all  the  reliable  analyses  compiled  by  Wolff  and  Knop,  up  to 
August,  1865,  witli  several  recent  ones  by  American  cliemists.  The 
table  shows  the  amount  of  volatile  matter,  and  each  mineral  sub- 
stance in  1000  parts. 


Substance. 

Volatile 
Matter. 



Potash. 

03 

O 

W. 

Magnesia. 

Lime. 

Phosphoric 
Acid. 

Sulphuric 
Acid. 

Silica. 

Chlorine. 

980 

20 

6 

25 

0.70 

2 

44 

0 

62 

9.24 

0.48 

0 

34 

.  ..* 

986 

14 

3 

78 

0.21 

2 

04 

0 

37 

6.25 

0.15 

0 

30 

970 

30 

4 

77 

1.14 

2 

19 

1 

14 

6.21 

0.48 

13 

92 

Rice  

995 

5 

1 

16 

0.24 

0 

.67 

0 

14 

2.55 

0.03 

0 

15 

Rye  

980 

20 

6 

18 

0.36 

2 

18 

0 

54 

9.50 

0.46 

0 

30 

975 

25 

5 

58 

0.71 

2 

.11 

0 

63 

8.36 

0.58 

6 

93 

986 

14 

2 

66 

0.81 

2 

60 

7.50 

0.21 

Buckwheat  

990 

10 

2 

31 

0.62 

1 

34 

6 

33 

4.80 

0.36 

6 

ii 

o'.oi 

972 

28 

11 

24 

1.03 

2 

24 

1 

17 

10.16 

0.98 

0 

25 

0.64 

Yield  beans  

965 

35 

14 

17 

0.42 

o 

.34 

1 

82 

13.72 

1.78 

0 

42 

1.01 

963 

37 

11 

24 

1.44 

5 

.01 

3 

84 

12.17 

1.39 

0 

39 

0.61 

987 

13 

4 

22 

1.06 

1 

.14 

3 

02 

1.30 

0.62 

0 

18 

0.90 

945 

55 

19 

41 

0.66 

3 

02 

5 

77 

4.45 

2.88 

21 

90 

Wheat  straw  

950 

50 

5 

75 

1.45 

1 

30 

3 

10 

2.70 

1.45 

33 

15 

Corn  cobs  

972 

28 

13 

39 

0.33 

1 

14 

0 

95 

1.23 

0.52 

7 

50 

952 

48 

8 

97 

1.58 

1 

48 

3 

69 

2.25 

0.91 

27 

88 

943 

57 

12 

42 

3.02 

4 

38 

21 

61 

4.44 

3.19 

3 

24 

3 '.47 

Barley  straw. . . . 

949 

51 

11 

01 

2.29 

1 

22 

3 

37 

2.19 

1.88 

27 

43 

929 

71 

31 

52 

2.69 

5 

51 

16 

40 

4.97 

0.14 

3 

83 

9 '.79 

760 

240 

65 

76 

8.88 

25 

20 

88 

80 

8.64 

9.36 

13 

04 

10.80 

949 

51 

11 

22 

2.70 

2 

04 

4 

18 

2.14 

1.78 

24 

83 

923 

67 

23 

11 

1.07 

8 

17 

22 

78 

6.83 

2.01 

1 

80 

2*.  47 

Lucern  

973 

71 

17 

95 

0.78 

4 

11 

34 

08 

6.03 

4.33 

1 

42 

1.35 

Potato  (Irish)... 

963 

37 

22 

12 

0.59 

1 

60 

0 

75 

7.06 

2.44 

0 

85 

1.03 

932 

68 

36 

10 

10.06 

3 

46 

3 

12 

6.42 

2.24 

2 

24 

4.48 

Rutabagas  

923 

77 

39 

42 

5.15 

2 

00 

7 

46 

11.78 

6.46 

0 

38 

3.92 

White  turnips.. . 

928 

72 

36 

43 

2.73 

1 

51 

9 

64 

12.52 

4.32 

0 

79 

4.60 

Linseed  cake  

938 

62 

14 

44 

0.86 

9 

85 

5 

33 

21.88 

2.10 

4 

03 

0.37 

Wheat  bran  

936 

64 

15 

36 

0.38 

10 

75 

3 

00 

33.15 

0 

70 

Rape  cake  

934 

66 

16 

03 

0.08 

7 

59 

7 

19 

24.35 

2.17 

5 

74 

6.13 

Cotton-seed  cake 

930 

70 

24 

78 

3 

01 

3 

22 

33.81 

0.77 

2 

80 

*  In  a  number  of  analyses  chlorine  was  not  estimated,  as  the  dots  indicate, 
t  This  is  probably  the  garden  pea,  as  our  field  pea  is,  botanically  speaking,  a 
bean,  and  the  analysis  of  the  field  bean  represents  more  nearly  our  cow  pea. 


APPENDIX. 


401 


Table  IL 

Showing  the  Proximate  Composition  of  Agricultural  Plants  and 
Products,  embracing  the  average  of  water,  albuminoids,  carbo- 
hydrates, crude  fibre,  fat,  etc.,  and  of  nitrogen,  1000  parts,  by  Profs. 
Wolff  and  Knop. 


Substance. 

Water. 

Organic  Matter. 

1 

Albuminoids. 

Carbo-hydrates. 

Crude  fibre.  * 

Fat,  etc.  t 

1 

Nitrogen. 

Wheat  

144 

836 

130 

676 

30 

15 

20.50 

144 

835 

100 

680 

55 

70 

16.00 

Oats  

143 

827 

120 

609 

103 

60 

19.20 

146 

849 

75 

765 

9 

5 

12.00 

Rye  

143 

837 

110 

692  - 

35 

20 

17.60 

143 

834 

90 

659 

85 

25 

14.40 

140 

830 

145 

621 

64 

30 

13.20 

i3iickwheat 

140 

836 

90 

596 

150 

25 

14.40 

143 

832 

224 

523 

92 

25 

35.84 

Beans  (field)  

145 

820 

255 

455 

115 

20 

40.80 

143 

802 

20 

302 

480 

15 

3.20 

143 

825 

15 

270 

540 

13 

2.40 

143 

802 

20 

298 

484 

14 

3.20 

143 

807 

25 

382 

400 

20 

4.00 

143 

817 

65 

.352 

400 

20 

10.40 

173 

777 

102 

335 

340 

10 

16.28 

140 

820 

30 

390 

400 

11 

4.80 

Pea  hull  

143 

797 

81 

366 

350 

20 

12.90 

103 

832 

105 

295 

370 

20 

16.80 

780 

203 

37 

86 

80 

8 

5.92 

740 

240 

45 

70 

125 

7 

7.20 

950 

241 

20 

21 

11 

3 

3.20 

880 

111 

11 

91 

9 

1 

1.76 

870 

120 

16 

93 

11 

1 

2.56 

915 

77 

8 

59 

10 

1 

1.28 

131 

818 

140 

500 

178 

38 

22.40 

115 

806 

283 

413 

110 

100 

45.28 

126 

867 

118 

741 

7 

12 

18.88 

*  Crude  fibre  represents  impure  cellulose. 

t  Fat,  etc.,  includes  with  fat,  wax,  chlorophyl,  and  in  some  cases  the  resins. 
t  The  field  bean  of  Europe  probably  approaches  nearer  our  field  pea  than  the 
European  pea. 


408 


APPENDIX. 


Table  III. 

Average  composition,  per  cent,  and  per  ton,  of  various  kinds  of 
produce,  with  tlieir  estimated  value  as  manure,  from  amount  of 
nitrogen,  phosphoric  acid,  and  potash,  taken  from  a  table  prepared 
by  John  B.  Lawes,  of  Rothamstead,  England. 


Substance. 

Per  Cent. 

Pounds  per  every  Ton. 

Value  as  manure,  in  dollars 
and  cents. 

Mineral  Matter. 

Phosphoric  Acid,  estimated 
as  Phosphate  of  Lime. 

Potash. 

Nitrogen. 

Dry  Matter. 

Mineral  Matter. 

Phosphate  of  Lime. 

Potash. 

Nitrogen. 

7.00 

4.92 

1.65 

4.75 

1.971 

156.8 

110.2 

37.0 

106.4 

*19.72 

tOotton  seed  cake. 

8.00 

7.00 

3.12 

6.50 

1.994 

179.2 

156.8 

70.0 

145.6 

27.86 

3.00 

2.20 

1.27 

4.00 

1.882 

67.2 

49.3 

28.4 

89.6 

15.75 

2.40 

1.84 

0.96 

3.40 

1.893 

53.8 

41.2 

21.5 

76.2 

13.38 

Indian  meal  

1.30 

1.13 

0..35 

1.80 

1.971 

29.1 

25.3 

7.8 

40.3 

6.65 

Wheat  

1.70 

1.87 

0..50 

1.80 

1.904 

38.1 

42.0 

11.2 

40.3 

7.08 

2.20 

1.35 

0.55 

1.65 

1  882 

49.3 

30.2 

12.3 

37.0 

6.32 

Oats  

2.85 

1.17 

0.50 

2.00 

1.926 

63.8 

26.2 

11.2 

44.8 

7.70 

6.60 

7.95 

1.45 

2.55 

1.926 

147.8 

178.1 

32.5 

57.1 

14.59 

7.50 

1.25 

1.30 

2.50 

1.882 

168.0 

28.0 

29.1 

56.0 

9.64 

Bean  straw  

5.55 

0.90 

1.11 

0.90 

1.848 

124.3 

20.2 

24.9 

20.2 

3.87 

Meadow  hay  

6.00 

0.88 

1.50 

1.50 

1.882 

134.4 

19.7 

33.6 

33.6 

6.43 

5.00 

0.55 

0.65 

0.60 

1.882 

112.0 

12.3 

14.6 

13.4 

2.68 

Barley  straw  

4.50 

0.37 

0.63 

0.50 

1.904 

100.8 

8.3 

14.1 

11.2 

2.25 

5.50 

0.48 

0.93 

0.60 

1.859 

123.2 

10.7 

20.8 

13.4 

2.90 

1.00 

0.09 

0.25 

0.25 

.280 

22.4 

2.0 

5.6 

5.6 

1.07 

0.68 

0.13 

0.18 

0.22 

.246 

13.4 

2.9 

4.0 

4.6 

91 

0.68 

0.11 

0.29 

0.18 

.179 

15.2 

2.5 

6.5 

4.0 

86 

1.00 

0.32 

0.43 

0.35 

.537 

22.4 

7.2 

9.6 

7.8 

1.50 

*  These  values  are  based  upon  the  prices  of  guanos  and  superphosphates  in 
England.   They  are  25  per  cent,  higher  in  the  United  States. 

t  This  article  of  Southern  production  has  more  phosphoric  acid,  more  potash, 
and  more  nitrogen  than  any  other,  and  is  worth  considerably  more  in  dollars  and 
cents. 


APPENDIX. 


409 


^  : 

'A 

^1 

13 

:m 

^  ?;  5 


r;  :t 


s   s  ^ 


^    g   -   5   3  z 


— 

^     ^  ^ 


Z^,  -fi  ^ 


o 

5    ^   ^    5  ^§ 


:m  c 


1-       Ci  -1  — 

—  :m  t= 


i:    ?5  H 


r-.      o      i-t      c-t  i-- 

H   ^  ;^  ^ 


^  £i  ?i 


^  ^  ^ 


21 


18 


I 

i 
I 


J 1 J 


1 
■I 

H 


410 


APPENDIX. 


TABLE  V. 


Fruits  arranged  according  to  the  proportion  of  Acid,  Sugar, 
Pectin  (jelly),  and  Gum  ;  averages  from  Fresenius  ;  acid  being  1 : 


Acid. 

Sugar. 

irectiii  auQ. 
Gum. 

1 

1.6 

3.1 

1 

1.7 

6.4 

1 

2.3 

11.9 

Raspberries  .  ....   

1 

2.7 

1.0 

1 

3.0 

0.1 

1 

3.7 

1.2 

1 

4.3 

0.4 

1 

4.4 

0.1 

1 

4.9 

0.8 

1 

4.9 

1.1 

1 

6.9 

1.4 

1 

7.0 

4.4 

1 

11.2 

5.6 

1 

17.3 

2.8 

1 

20.2 

2.0 

1 

94.6 

44.4 

TABLE  VI. 

Standard  weight,  per  bushel,  for  grain,  seed,  etc.,  in  most  cases 
established  by  law  in  a  number  of  the  States  of  the  Union  : 

Pounds. 

Peas   60 

Irish  potatoes   60 

Onions   60 

Clover  seed   60 

Timothy  seed   44 

Flax  seed   56 

Dried  apples  23 

Dried  peaches,   83 

Sweet  potatoes   55 


Pounds. 

Indian  corn   56 

Wheat   60 

Eye   56 

Oats   33 

Barley   48 

Buckwheat   48 

Beans   63 

Cotton  seed  28 

Corn  on  the  cob   70 


Table  VII. 

Showing  the  amount  of  different  kinds  of  wood  and  coal  required 
to  throw  out  a  given  amount  of  heat,  demonstrated  by  experiments 
of  Marcus  Bull,  of  Philadelphia. 


Cords. 

Hickory  Wood.   4 

White  Oak   4| 

Hard  Maple   6| 

Soft  Maple   74 


Cords. 

Pitch  Pine   91. 

White  Pine   9^ 

Anthracite  Coal  4  tons. 

Bituminous  Coal  5 


PAGE 

Absorbent  power  of  soils  105,  109 

"  clay   107 

"         "  sand   107 

Absorption  of  soils   237 

" ,  water   46 

Aceiic  acid   210 

Acetification   212 

Acid,  acetic   210 

"    carbonic   14S 

citric   210 

"   huraic   257 

'*   hydrochloric   158 

"   hydrous  sulphnric   290 

malic   209 

"   nitric   151 

"    oxalic   210 

metapectic   196 

'*   pectic   193 

"   prussic   213 

Acids   142 

"   and  bases   2C9 

"   vegclable   2:>9 

Acid  silicic   183 

"   sulphuric   Z03 

"    sulphurous   15S  ' 

"    sulphydric  15S  | 

"   tannic   210  | 

"   tartaric   210 

Adhesive  attraction   124  j 

Adhesiveness  of  soils   109  i 

Agricultural  division  of  soils   101  ' 

Agriculturist   13 

Agriculture  as  a  science   14 

"  an  art   14  j 

defined   13  | 

"      basis  of   15 

Air  expansion  by  heat   63  , 


PAGE 


Air  in  motion   89 

roots   22 

Akene,  the   35 

Albuminoids   190 

composition  of   193 

"         animal   1&4 

"         in  crops   194 

"         vegetable   194 

Alburnum   29 

Albumen    191 

Alcohol,  product  of  sugar   205 

Aleurone   193 

Alkalies   218 

Alkaloids   217 

Allotropism   143 

Alluvial  soils   101 

Alumina    178 

Ammonia   154,  276 

Ammoniated  phosphates  300 

Ammonia  and  nitric  acid  in  plants. .  270 

Ammonia  and  phosphoric  acid  com-  

bined   300 

Ammonia  as  a  solvent   282 

"      escape  of  from  soils  277 

from  nitric  acid  274 

formation  of  in  soils  276 

"      in  atmosphere   155 

in  soils   242,  243 

'*      in  rain-water   155 

*'      loss  of  in  soils   279 

"      not  efficient  by  itself   279 

relations  to  vegetation  . .  '155 

nitrate  of   277 

superior  to  the  nitrates. .  280 

held  by  snow   74 

Anemometer   90 

Animal  charcoal   147 


412 


INDEX. 


PAGE 

-  Animal  albumen   192 

"    heat   343 

*'    nutrition   341 

substances,  composition  of.  341 

Analysis  of  cotton  seed   333 

soils   225 

"       '*  new  method  247 

Annuals   45 

Anther   33 

Apatite  284 

Aqua  fortis   151 

Arabin    200 

Artifical  milk   352 

Argol   210 

Ascending  and  descending  sap   222 

Ashes   325 

Ash  in  plants   161 

Atmosphere,  chemistry  of   141 

absolute  humidity   G4 

"         composition  of   141 

*'         density  of   61 

"         pressure  of   62 

properties  of   61 

'*         as  related  to  vegetation  60 

"         weight  of   61 

"         description  of   59 

**         moisture  of   63,  6G 

**         temperature  of   66 

Atmospheric  ingredients   158 

•*         tabular  view  of   176 

Attraction   124 

Bark   28 

Barometer   62 

Bassorin   200 

Barley  seed   37 

Bast  tissue   20 

Benefit  of  resting  lands  334 

Benefits  of  humus   263 

Berry,  the   35 

Best  rotation  in  cotton  336 

Biennials....-   45 

Bi-phosphate  of  lime   292 

solution  of  295 

Blade,  the   30 

Bone  black   147,  284 

Bone  phosphate  of  lime   285 

Botany,  agricultural   15 

Bottom  water   120 


Bread  grains,  sugar  in   204 

Breathing  pores   31 

Buds   32 

"   adventitious   33 

"   latent   33 

Bulbs   23 

Butter  making   351 

Cactus   30 

Cambium   27,  23 

Calcium   187 

Capillary  water   120,  121 

Carbon   146,  162 

"    fixation  in  plants   171 

"    in  plants   168 

Calcareous  soils   101 

Calyx   33 

Carbonates         ,   148 

Carbonic  acid   148 

"         *'  amount  of   149 

"  decomposition  of   169 

'*         "  exhalation  of   172 

"         *'  as  a  solvent   175 

"         "  supply  of   173 

"         "  from  the  soil   174 

Carboniferous  system   97 

Carbonic  oxide   158 

Caffeine    219 

California  moss   213 

Camphor   215 

Cane  sugar   201 

Carbo-hydrates   ICS 

Casein   192 

Cattle  foods   344 

"      "    analysis  of   358 

"    as  provender   357 

Caustic  potash   186 

Causes  of  rain   80 

Cereals,  unripe  seed   37 

Cellular  tissue   20 

Cellulose   196,  18 

Ceraline   193 

Cerasine   200 

Chemistry  of  the  atmosphere   141 

plants   160 

"       "        soils  224 

Chemical  qualities  of  soils  205 

"  changes  in  manure  heaps  .  317 
Changes  in  vegetable  tissues   175 


INDEX. 


413 


PAGE 

Chlorine   188,  310 

Chlorides   189 

Chloride  of  sodium   188,  311 

potassium   186,  3C3 

Chlorophyl   220 

Cirro-cumulous  clouds   79 

Cirro-stratus      "    79 

Cirrus  '*    77 

Citric  acid   210 

Circulation  of  sap   51 

Classes   16 

Clay  soils   101 

'*     "   absorption  of   238 

absorptive  power  of   107 

Climate,  effect  on  humus  ,  256 

Clouds,  combined   79 

"      formation  of   76 

'*      original   77 

Cocoanut   39 

Coarse  and  fine  soils   231 

Coffee  berries.   36 

Colluvial  soils   101 

Coloring  matter  of  plants  219 

Color  of  plants  by  electricity   87 

"    "   soils   112 

Composite  plants   17 

Composition  of  the  atmosphere   141 

Composting  manures   314 

Condensed  milk   353 

*'       oxygen   143 

Constituents  of  plants   226 

"  *'     "   in  minerals...  228 

"  seeds   227 

Contractility   58 

Coprolites'   284 

Cork   28 

Corn,  exhaustion  by   234 

"    starch   198 

Corolla   33 

Cotton,  best  rotation  with  336 

*'    exhaustion  by  234 

seed  analysis  of   323 

"      "   as  a  manure   323 

"      "   meal   355 

Cotyledon   36 

Cremor  tartar   210 

Cretaceous  system   36 

Crops,  rotation  of   235,  330 


PAGE 

Cruciferous  famiJy   17 

Crucif  era  ,   36 

Crude  fibre,  digestion  of   349 

Cryptogams   16 

Culms    25 

Culture,  horizontal...   138 

Cumulo-stratus   79 

Cumulus  clouds   78 

Cyanogen   157 

Cyanophyl   220 

Decay   259 

Deductions  from  experiments   337 

Density  and  course  of  sap   221 

Dew   71 

Dextrine   1G9 

Diastase   261 

Diffused  light,  effect  of   172 

Digestion  of  crude  fibre   340 

Dioecious  plants   34 

Disintegration   C8 

Ditching   131 

Divisibility  of  soils   110 

Drainage  ,   128 

at  the  South   131 

Drain  tiles   131 

Drift  soils   101 

Drupe   34 

Earth  closets   320 

division  of   94 

"    how  warmed   67 

"    temperature  of   95 

Elastic  sandstone   97 

Electrical  force   58 

Electricity  aids  germination   86 

effect  on  colors   87 

Elements,  inorganic,  in  plants   177 

Embryo,  the   35 

Endogens   16,  36 

Endosperm   35 

Eocene  sea   G8 

Epidermis   26 

Eremacausis   143,  260 

Essential  oils   214 

Evaporation   64 

Excretory  roots   24 

Exhalation  of  carbonic  acid   172 

"  Avater   49 

Exhaustion  of  soils   233 


V 


INDEX. 


414 


PAGE 

Exogens   16 

Experiments  in  1873    337 

"  "  Germany  341 

"         with  cotton  seed   324 

"  "    fertilizers  281 

"      with  reduced  phosphates  299 

"Families  ;   16 

Farmer   13 

Farm-yard  manure  317,  318 

Fat  former.^   342 

Fat  in  vegetables   216 

Fattening  animals   347 

Feeders   21 

Fermentation   261 

Ferruginous  soils   105 

Fertility,  dubious  tests  of   246 

"      other  requisites  of   230 

tests  of   251,  254 

"      organic  matters  essential. .  262 

Fertilizers  and  natural  manures  265 

"         hastening  maturity  268 

"         how  divided   266 

Fibrils   21 

Fibrin   192 

Fixation  of  carbon   171 

Fixed  oils   213,  214 

Flesh  building,  laws  of  346 

Flesh  formers   342 

Flower  buds  ..    32,  33 

Flower,  the    33 

Flowers  of  sulphur   185 

Fluids,  circulation  of   46 

Fodder  corn   356 

Fogs   69 

Foliage,  offices  of   31 

Forces   15 

Frost   72,  100 

Frost  smoke   70 

Fructose  ..203 

Fructification   34 

Fruit,  of  the   34 

Fruit  sugar   203 

Fuel  and  food  of  animals  353 

Full  moon,  elfects  on  weather   92 

Gas  light  carburetted  hydrogen  166 

Gases    60 

Genera   16 

Geology   94 


PAGE 

Geology  of  Georgia   97 

Geological  division  of  soils   100 

Germination   38 

Gilliflower   37 

Glaciers   100 

Gliadine   193 

Glucose   202 

Glucosides   203 

Glutine   191 

Glycerine  216 

Gourd  fruits   35 

Grains   35 

Gravelly  soils   105 

Grandeau's  experiments  248 

"         theory  tested  250 

Green  manures  >  326 

Grape  sugar   202 

Granite   175 

Gums,  the   196,  200 

Hail    75 

Heart  wood   29 

Heat,  radiation  of   67 

Herbs    45 

Honey  dew   204 

Home-made  superphosphates  293 

Horizontal  culture   138 

Humic  acid    257 

Humus  in  soils   255 

"      benefits  of   263 

"      absorbing  power  of   108 

Hurdling  system   331 

Hybrids   16 

Hydrochloric  acid   158 

Hydrogen    146,  102 

"         in  plants    165 

Hydrocyanic  acid   213 

Hydrostatic  water   120 

Hygroscopic  water   120,  121 

"        power  of  soils   117 

Hygrometer    65 

Hypo-phosphoric  acid   185 

Ice,  law  of   237 

Importance  of  mineral  elements  177 

Inside  growers   26 

Inorganic  elements  in  plants   177 

Inulin   198 

Iodine  -   180 

Iron,  carbonate  of    181 


INDEX. 


PAGE 

Iron  peroxide  of   180 

"   protoxide  of    99 

"   importance  to  plants   180,182 

Isomeric  bodies    208 

Jellies   196 

Kernel,  the   35 

Lactose   203 

Land  hemisphere    94 

"    plaster  on  clover   157 

Laws  of  flesh  building   346 

Leaf  buds   32 

Leaves   30 

Legume,  the   35 

Leguminosa   36 

Legumine   191 

Leucophyl   20 

Levulose   199 

Light,  lunar   93 

"    eifect  on  oxygen   164 

"    on  vegetation   87 

Lignin   197 

Lime  CaO   306,  187 

in  soils   225 

soils   103 

sulphate  of   308 

"     carbonate  of   307 

Lingula   287 

Loamy  soils   101,  104 

Lunar  influence    91 

Magnesium   188 

Magnesia,  MgO   308 

Malic  acid   209 

Mannite   204 

Manures,  composting  314 

"       heaps,  changes  in   317 

"       natural   312 

Manganese   179 

Margarin   215 

Marsh  gas   158 

Marls   104 

Marly  soils   101 

Maize  seed   37 

Melon  seeds   37 

Metallic  oxides  in  plants   177 

Mechanical  action   99 

Mercurial  gauge   55 

Meteorology,  agricultural   59 

Metapectic  acid   196,  206 


PAGE 

Milk  sugar   203 

"   production  of   349 

"    artificial   352 

"   ducts   28 

Minerals,  in  organic  matter  327 

in  plants    177,328 

value  of   329 

"       exhausted  by  crops  234 

"       plant  constituents  in  ....  228 

"       period  of  exhaustion  229 

"       constituents  per  acre  229 

"       phosphates,  origin  of  286 

"       composition  of   287 

Mineral  theory   233 

Miasma   129 

Mists   69,  71 

Mixing  cattle  foods   345,  354 

Monoecious  plants   33 

Monocotyledenous  plants   21 

Moon,  influence  of   91 

Mountains,  height  of   94 

Mucidine   193 

Mucilage,  vegetable   SOO 

Mycose   204 

Natural  manures   312 

'*     system   16 

Nevasa  guano   288 

Nicotine   190,218 

Nimbus  clouds   79 

Nitric  acid   157 

"      "by  electricity   86 

generation  of   142 

"      "  in  rain  water   154 

'Mn  soils   242,  244 

"      "its  importance  275 

Nitrification   271 

"        conditions  essential  ...  273 

Nitric  peroxide   152 

Nitrates   153 

Nitrate  of  soda   116 

Nitre  beds   274 

Night  soil   319 

Nitiites   153 

Nitrogen   150,  162 

"      in  rain  water   159 

"      in  ash  of  plants   163 

"      in  plants   165 

"      not  absorbed  by  plants —  167 


416 


INDEX. 


PAGE 

Nitrogen  exhausted  by  crops  234 

"      iu  soils  239,  241 

"      as  a  fertilizer   269 

'*      amount  requisite  271 

*'      forms  of  in  plants  269 

"      absorption  of  329 

Nitrof,'eneous  compounds   193 

Nitrous  oxide  , . .  158 

Nodes   25 

Nucleolus   18 

Nucleus   18 

Nut,  the  *   35 

Nutritiousness  of  wheat  bran  355 

Oats,  exhaustion  by  234 

' '    volunteer   332 

Offices  of  roots   23 

Oil  of  vitriol  •  291 

Oils,  vegetable   214 

"    essential   214 

*'    fixed   215 

"    volatile,   214 

Olein   215 

Orchids   22 

Orders   16 

Organs  of  plants   20 

Organic  and  inorganic  parts   161 

"     matters  in  air   158 

"     elements  in  plants   162 

Organism  of  plants   161 

Organic  nitrogen  in  soils  240 

matter,  solubility  by  253 

"         "      climate  on   256 

"         "      essential  to  fertility  262 

Outside  growers   27 

Oxalic  acid   210 

Oxide  of  magnesium   188 

Oxides   142 

Ovaries   33 

Ovules   33 

Oxygen   142,  162 

"      in  plants   163 

"      transmission  of   164 

Ozone   143 

"   relations  to  vegetation   145 

"   by  electricity   86 

Palmatin   215 

Papilionaceous  family   17 

Petals   33 


PAGE 

Peas,  exhaustion  by  234 

Peaty  soils   104 

Peruvian  guano   240,  301 

Pecticacid   190 

Pectin   196,  205,  206 

Pectose  group   196,  206 

Perennials   45 

Finite   204 

Pistils   33 

Pith   27 

"   rays   28 

Phenogams.    16 

Phosphate  of  lime,  precipitated  296 

Phosphates,  ammoniated  300 

'*         reduced   297 

"         composition  of . . . .  287,  288 

Phosphoric  acid   185,  283,  285 

"       sources  of   283 

"       anhydride   184 

Phosphorous  acid   185 

"         anhydride   184 

Phosphorus   184 

Physical  qualties  of  soils   105 

Phosphorized  fats   216 

Phloridzin   202 

Plants,  coloring  matters  of  219 

"      supply  of  water   122 

"      absorption  of  water   123 

"      chemistry  of   160 

"      oxygen  in   163 

"      hydrogen  in   165 

"      carbon  in   168 

"      nitrogen  in   166 

character  and  duration  of  . .  45 

"      differently  constituted  333 

"      one  celled   19 

Plant  life,  processes  of   44 

Plains   94 

Plantlet,  growth  and  nutrition   42 

Plaster  of  Paris   308 

Plateaus   94 

Ploughing,  benefits  of   134 

Ploughs   133 

Pluviometer   84 

Plumule   35 

Pods   35 

Pollen   33 

Polar  fogs   70 


I 

PAGE 

Pome   34 

Porcelain  clay   99 

Polycotj'ledons   36 

Potash,  hydrate  of   186 

Potassa,  KO   302 

Potassium   186 

chloride   303 

Potato,  Irish   197 

Poiidrette   320 

Preface   9 

Precipitated  phosphate  of  lime  299 

Protein   191 

Protagon   216 

Proximate  principles   190 

*'  changes  in  207 

Protoplasm   18 

Prosenchyma   20 

Proximate  composition  of  animals.  341 

Provender,  relative  value  357 

Pruning   55 

Prussic  acid  213 

Pyrolusite   179 

Quartz   182 

Qucrcite   204 

Quicksilver   307 

Quinia   190 

Radicle   35 

Rain,  causes  of   80 

"     gauge   84 

*'     sources  of   85 

*•     fall,  amount  of   82 

Red  snow   19 

Reduced  phosphates   297,  299 

Requisites  of  fertility   230 

Rennet    192 

Reproductive  organs   20 

Resin   ;  215 

Respiration  apparatus   348 

Resting  lands,  benefits  of  334 

Retentive  power  of  soils    118 

Rind   28 

Rotation  of  crops   330,  335 

"       "  seeds   333 

Rock  crystal    182 

Rocks,  stratified,  etc   95 

Root  hairs    22 

Roots   21 

Root  stocks   26 

18* 


417 


PAGB 

Runners   25 

Rye  seed    37 

Saccharine  substances   203 

Saccharose    201 

Saleratus   148 

Salt,  common   311 

Salts,  absorbed  by  soils   107 

Sap,  ascending  and  descending  222 

"    density  and  course  221 

"    chemical  composition  of  223 

"   circulation  of   51 

Salacin  190,  202 

Saponification   215 

Sand,  absorptive  power  of  107,  108 

Sandy  soils   101 

Sea  breese    68 

Sea  water   150 

Serum   192 

Scries   16 

Sepals   33 

Seeds   35,  37 

"     germination  of   37,  38 

"     depth  for  planting    41 

"     and  plant  constituents   227 

"     rotation  of   333 

Sensitive  plant   58 

Sheep  husbandry   321 

Sprinkling  of  soils   110 

Shrubs   45 

Sieve  cells   28 

Silica  182 

Silicates  .\.  183 

Silicic  acid   1S3 

Silica,  decomposition  of   99 

Silicious  soils   103 

Silver  grains   28 

"     mines   99 

Snow   73 

Soils,  classification  of   100 

"    absorptive  power  of  106,  108 

"    chemical  qualities  of   105 

"    alluvial    101 

"    agricultural   101 

"    adhesiveness  of   109 

"    drift   101 

"    divisibility  of   110 

"    depth  of   96 

**    geological  division   100 


418 


INDEX. 


PA  GE 

Soils,  coarse  and  fine   118 

*'    color  of   112 

"    capacity  for  heat   113 

"    hygroscc  pic  power  of  ,..  117 

"    ab'  to  heat    Ill 

calcareous —   101 

"    as  related  to  physics   94 

"    loamy   101,  104 

"    power  to  absorb  salts   107 

"    clay   101,  102 

"    colli!  vial   101 

"    specific  gravity  of   106 

"    peaty    104 

sedentary   101 

"    as  to  water   Ill 

"    marly   101.  103 

"    sandy   101 

"    transported   100 

physical  qualities  of   105 

"     silicious   102 

"    weight  of    105 

permeability  to  water   114 

"    retentive  power  of   118 

"  "  for  heat   113 

"    hygroscopic  power  of   117 

"    shrinking  of   Ill 

"    American  and  European  224 

"    analysis  of   225,  246 

"    plant  constituents  in  226 

"    coarse  and  fine   231 

"  „  exhaustion  of   233 

"    soluble  and  insoluble   231 

"    analysis,  new  method        247,  251 

"    ammonia  in   243 

"    chemical  absorption  of   237 

"    soluble  matters  in  232 

nitrogen  in  .239,240 

"    nitrogen  compounds  in  241 

nitric  acid  in   244 

"    nitrous  acid  in  245 

"    rich  and  poor    251 

Soda  essential  to  plants   187 

"    carbonate  of   116 

"    common   187,  304 

"    nitrate  of   116 

Sodium,  peroxide  of   187 

chloride  of    187 

Soil  roots   22  , 


IA.GE 

Solar  light  or  carbonic  acid  . . . 

  239 

Solubility  by  organic  matter. . . 

 253 

a  test  of  fertility  .. , 

196,  197 

63,  157 

....  29 

of  the  

....  26 

.  26,29 

....  26 

"          "     composition  of  . . 

313,  318 

....  33 

....  26 

87,  170 

"      efiect  on  carbonic  acid 

....  89 

. . . .  99 

...  308 

....  309 

Superphosphates,  composition  of  . .  292 

"  home-made 

...  293 

"              manufacture  of  . .  289 

...  158 

...  115 

...  94 

"    atmospheric  ingredients  , 

...  176 

...  194 

Tannic  acid  

...  210 

...  202 

...  210 

r 


INDEX. 


419 


Temperature  

*'         of  soils   Ill 

"        in  germination   39 

Tertiary  system  •••  98 

Theine  '^^^^ 

Theobromine   


Thermometer 


68 


Thunder  heads  

Tiles  for  drainage   131 

Tilth    101 

Trade  winds   90 

Trenching   132 

Trees  

Tubers  

Turnips,  experiments  on   321 

Umbelliferous  plants   17 

Under-draining    131 

Yapor  of  water   03,  157 

Vascular  tissue   20 

Varieties  

Vegetable  acids   209 

albumen   191 

casein   192 

"         cells   17 

"        fibrin    193 

moulds   101,104 

"        mucilage   200 

oils   214 

"    '     tissues   19 

"         changes  in   175 

Vegetable  organs   20 

Venus' s  fly  trap   ^8 


Vinegar. 


212 


Vital  force   57 

Volatile  alkali   155 


PAGE 

Volatile  oils  214« 

Waste   98,99 

Water,  absorption  of   46 

"      amount  in  plants   125, 126 

bottom   120 

"      exhalation   49 

capillary   120 

"      chemistry  of   235 

"      hemisphere   94 

how  formed  236 

"      how  plants  absorb  122 

hydrostatic   120 

"      hygroscopic   120 

gaseous,  liquid,  solid  236 

in  the  soil   120,126,130 

"      of  crystallization  236 

"      physical  offices  in  plants  ...  127 

"      supply  to  plants   122 

Wax   215 

Weathering   335 

Weight  of  soils   105 

Wheat  bran,  nutritiousness  of   355 

flour,  analysis  of  355 

"     seeds   36,  38 

Wind,  cause  of   89 

velocity  of....   90 

Wood  ashes   325 

"      tissue   20 

growth  of   44 

Woody  fibre   196 

Yeast  fungus  261 

Zamia  spiralis   22 

Zanthophyl  220 

,  Zeolites   138 


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